Until nearly fifty years after the establishment of the
British Museum, meteorite collections nowhere existed, for
the reports of the fall of stones from the sky were then
treated as absurd, and the exhibition of such stones in a
public museum would have been a matter for ridicule; a few
stones, which had escaped destruction, were scattered about
Europe, and were in the possession of private individuals
curious enough to preserve bodies concerning the fall of
which upon our globe such reports had been given. Hence it
happened that in 1807 not more than four meteoric stones
were in the British Museum: three of them, Krakhut, Wold
Cottage and Siena, had been presented in 1802-3 by Sir Joseph
Banks; the fourth was a stone of the L'Aigle fall, presented
in 1804 by Prof. Biot, the distinguished physicist. A fragment
of the mass met with by the traveller Pallas had been
presented by the Academy of Sciences of St. Petersburg as
early as 1776; this, and the fragments of Otumpa and
Senegal River, were long regarded by scientific men as
specimens of "native iron," and of terrestrial origin.
In the year 1807, happily for the future development of
the Mineral Collection, Mr. Charles Konig (formerly König)
was appointed Assistant-keeper, and six years later was
promoted to the Keepership of the then undivided Natural
History Department; it thus came about that for thirty-eight
years the senior officer of the Natural History Department
of the Museum was one who had an intense enthusiasm
for minerals and made them his own special study. It was
in Mr. Konig's time that Parliament voted (1810) a special
grant of nearly £14,000 for the purchase of the minerals
which had belonged to the Rt. Hon. Charles Greville; with
these passed into the possession of the Trustees fragments
of seven meteorites, including Tabor, which had been acquired
by Mr. Greville with the mineral cabinet of Baron
Born. The increase of the Natural History Collections was
such that in 1827 the Botanical, and in 1837 the Zoological,
specimens were assigned to special Departments, after which
Mr. Konig, as Keeper of "Minerals (including Fossils),"
was left free to devote his attention to those parts of Natural
History to which he was more particularly attached.
During Mr. Konig's Keepership, though numerous and
excellent mineral specimens were acquired, no great effort
was made to render the meteorite collection itself complete;
at his death in 1851, 70 falls were represented by specimens.
The following had been presented:—
Stannern: by the Imperial Museum of Vienna, in 1814.
Red River: by Prof. A. Bruce, in 1814.
Mooresfort: by Mr. J. G. Children, F.R.S., in 1817, and
by Dr. Blake, in 1819.
Adare: by Dr. Blake, in 1819.
The large Otumpa iron, and a piece of the Imilac
siderolite: by Sir Woodbine Parish, K.C.B., F.R.S., in 1826
and 1828 respectively.
Bitburg: by Mr. Henry Heuland, in 1831.
Krakhut: by Mr. Wm. Marsden, in 1834.
Cold Bokkeveld meteorite: by Sir John Herschel, Bart.,
F.R.S., Sir Thos. Maclear, F.R.S., and Mr. E. Charlesworth,
in 1839 and 1845.
Zacatecas: by Mr. T. Parkinson, in 1840.
Akbarpur: by Captain P. T. Cautley, in 1843.
Braunau and Seeläsgen: by the Royal Society, in 1848.
After the death of Mr. Konig, Mr. G. R. Waterhouse,
palæontologist, was appointed Keeper of the composite
Department. It was natural that the palæontological side
should then have its turn of special development, and in fact
the palæontological collections, already important, increased
from that time with great rapidity; the mineralogical side,
however, had additions made to it, though not in the proportion
allotted during the preceding years. During the
Keepership of Mr. Waterhouse (1851-7), only specimens of
two additional meteorites were added to the collection; one
of them, Madoc, was presented in 1856 by Sir Wm. E. Logan,
F.R.S.; also additional fragments of Imilac were presented
by Mr. W. Bollaert in 1857.
In the year 1857, a further division of the Natural History
Collections took place; the mineralogical and the palæontological
specimens being assigned to special Departments, and the
Minerals placed in the Keepership of Prof. Story-Maskelyne.
Under him the Mineral Collection was rendered as complete
as possible in all its branches; and it is owing entirely to
the unflagging energy he displayed, both in the search for,
and in the acquisition of the best obtainable specimens, that
the Mineral Collection was brought to its present position of
general excellence. Perhaps the greatest relative advance
was made in the improvement of the Collection of Meteorites.
Perceiving that only half of the falls represented at Vienna
were represented in the British Museum, and that the
difficulty of making a fairly complete collection of such
bodies must increase enormously as time goes on, owing
to the absorption of the specimens by public museums,
Mr. Maskelyne immediately after his appointment tried to
fill up the gaps. In the first place, the meteorite collections
of Dr. A. Krantz, Mr. R. P. Greg, and Mr. R. Campbell,
and many meteorites belonging to Mr. W. Nevill and Prof.
C. U. Shepard, were acquired by purchase in 1861-2.
During the interval (1857-63), the whole or parts of many
meteorites were presented to the Museum:—
From Great Britain.—Perth: by Mr. W. Nevill.
From Russia.—Tula: by Dr. J. Auerbach of Moscow.
From India.—Bustee, Dhurmsala, Durala and Shalka: by
the Secretary of State for India.
Assam, Butsura, Futtehpur, Khiragurh,
Manegaum, Mhow, Moradabad, Segowlie
and Umballa: by the Asiatic Society of
Bengal.
Nellore and Parnallee: by Sir W. T.
Denison, K.C.B.
Kusiali and Pegu: by Dr. Thos. Oldham,
F.R.S.
Kaee: by Sir Thos. Maclear, F.R.S.
Dhurmsala: by Mr. G. Lennox Conyngham.
From Australia.—The large Cranbourne iron: by Mr.
James Bruce.
From South America.—Vaca Muerta: by Mr. W. Taylour
Thomson.
Imilac: by Mr. W. Bollaert.
An Atacama iron: by Mr. Lewis
Joel.
From North America.—Tucson: by the Town Authorities
of San Francisco.
During the same interval, exchanges were made with the
museums of Paris, Vienna, Berlin, Copenhagen, Heidelberg,
and Göttingen, through Professors Daubrée, Haidinger,
Rose, Hoff, Bunsen, and Wöhler, respectively: and also with
the following private collectors:—Dr. Abich of Dorpat, Dr.
J. Auerbach of Moscow, Mr. R. P. Greg of Manchester, Prof.
C. U. Shepard of New Haven, U.S.A., and Dr. Sismonda of
Turin.
The result was that by the end of 1863 the number of
meteoric falls represented in the collection was 204, and
thus had been almost trebled during Mr. Maskelyne's first
six years of office.
Meanwhile, although Mr. Maskelyne, with the help of a
single assistant (Mr. Thomas Davies), was then rearranging
the general collection of minerals according to a new system
of classification, time was found for a scientific examination
of the meteorites thus being acquired. At that time the
Department was without a chemical laboratory, and not even
a blowpipe could be used, owing to the necessity of guarding
against a possible destruction of the Museum by fire.
Hence recourse was had to the microscope, and as early as
1861, a microscope fitted with a revolving graduated stage
and an eye-piece goniometer was constructed, under the
Keeper's directions, for the examination of thin sections of
meteorites with the aid of polarised light.
Working in this way, and with the simplest chemical
tests, Mr. Maskelyne was the first to announce in 1862 the
discovery in the Bustee meteorite of a mineral, unknown in
terrestrial mineralogy, to which he gave the name of
Oldhamite, and in 1863, the more than probable occurrence
of Enstatite as an important meteoritic ingredient (Nellore).
This method of determining the mineral constituents of
a rock-section by means of the relation of the vibration-traces
to known crystallographic lines, thus first and of
necessity employed for the discrimination of the minerals in
meteorites, is now in general use in the investigation, not
only of meteoritic, but of terrestrial rocks. About the same
time, from the Breitenbach meteorite were extracted crystals
of Bronzite, which yielded the first crystallographic elements
obtained for that mineral: the measurements were made and
published by Dr. Viktor von Lang, then assistant in the
Department (1862-4) and now Professor of Physics at
Vienna.
The microscope was further applied to the mechanical
separation of the different mineral ingredients of a meteorite:
and by picking out in this toilsome manner the different
mineral ingredients from the crumbled material of the
Bustee aerolite, and from the residue of the Breitenbach
siderolite left after the iron had been removed by mercuric
chloride, the several silicates contained in these meteorites
were isolated for future analysis. From the particles of
colourless mineral thus obtained from the Breitenbach meteorite,
one kind was selected in 1867, of which the crystals
presented a zone of orthosymmetry containing two optic
axes, and yielded two similar cleavages in a zone perpendicular
to the former. This ingredient was afterwards (1869)
announced to consist wholly of silica, a substance which,
before the isolation of this mineral, was only known to
occur as quartz, when in crystals, and these belong to the
hexagonal system: to the new mineral Mr. Maskelyne
later assigned the name of Asmanite. In 1868 was published
by Vom Rath the discovery of a species of terrestrial
silica, the crystals of which were regarded as belonging to
the hexagonal system, though their angular elements were
distinct from those of quartz: this mineral, named by him
Tridymite, has since been found (1878) to present optical and
other characters inconsistent with true hexagonal symmetry,
and is probably identical in its specific characters with the
meteoritic asmanite.
Further, another mineral occurring as minute gold-yellow
octahedra in the Bustee meteorite was recognised as new to
mineralogy, and termed Osbornite.
It was not till 1867, when a laboratory was fitted up
outside the Museum precincts, that it became possible to
make a complete chemical examination of these materials,
which had been gradually prepared and carefully picked for
analysis. In that year the late Dr. Walter Flight was
appointed to assist in the laboratory-work of the Department,
and afterwards gave valuable help in the chemical
analysis of the above materials; the results were quite confirmatory
of those already obtained by aid of the microscope
and the simple tests.
Since the great increase made during the first six years
of Prof. Maskelyne's Keepership, the Collection has continued
to grow, though necessarily at a less rapid rate.
Of the specimens added after 1863, the following have
been presented:—
1864-7: Manbhoom, Muddoor and Pokhra: by Dr. Thos.
Oldham, F.R.S.
1864: Agra: by Mr. Wm. Nevill.
1864: Atacama (stone): by Mr. Alfred Lutschaunig.
1865-70: Jamkheir, Lodran, Shytal, Supuhee and Udipi:
by the Secretary of State for India.
1865: Nerft: by Prof. Grewingk.
1865: Ski: by Prof. Kjerulf.
1867-70: Goalpara, Gopalpur, Khetri, Moti-ka-nagla,
Pulsora and Sherghotty: by the Trustees of the Indian
Museum. Calcutta.
1867-75: Knyahinya and Zsadány: by the Hungarian
Academy of Sciences.
1869: Krähenberg: by Dr. Neumayer.
1871: Searsmont: by Dr. A. C. Hamlin.
1873: Fragments of thirteen meteorites already represented:
by Mr. Benj. Bright.
1874: Bethany (Wild): by the Trustees of the South
African Museum, Capetown.
1875: Amana: by Dr. G. Hinrichs.
1876: Shingle Springs: by Mr. E. N. Winslow.
1876: Rowton: by the Duke of Cleveland.
1877: Khairpur and Jhung: by Mr. A. Brandreth.
1877: Verkhne-Dnieprovsk: by Prof. Koulibini.
1878: Cronstad: by Mr. John Sanderson.
1878: Santa Catharina: by Prof. Daubrée.
1879: Imilac, Mount Hicks and Serrania de Varas:
by Mr. George Hicks.
1881: Middlesbrough: by the Directors of the North
Eastern Railway.
1882: Veramin: by the Shah of Persia.
1882: Vaca Muerta: by Mr. F. A. Eck.
1883: Ogi: by Naotaro Nabeshima, formerly Daimiô
of Ogi, Japan.
1885: Ivanpah: by Mr. H. G. Hanks.
1885: Youndegin: by the Rev. Charles G. Nicolay.
1885 et seq.: Ambapur Nagla, Bishunpur, Bori, Chandpur,
Dokáchi, Donga Kohrod, Esnandes, Gambat, Heidelberg,
Kahangarai, Kodaikanal, Lalitpur, Nagaria, Nammianthal,
Nawalpali, Pirthalla, Sindhri, Wessely and
Wöhler's iron: by the Director of the Geological
Survey of India.
1885: Lucky-Hill: by the Governors of the Jamaica
Institute.
1886: Nenntmannsdorf: by Dr. H. B. Geinitz.
1886: Jenny's Creek: by Mr. John N. Tilden.
1887: Djati-Pengilon: by the Government of the
Netherlands.
1887, 1906: Albuquerque: by Dr. Richard Pearce.
1889: Bhagur and Kalambi: by the Bombay Branch of
the Royal Asiatic Society.
1890: Bendegó River: by the Director of the National
Museum, Rio de Janeiro.
1891: Dundrum: by the Board of Trinity College,
Dublin.
1891: Farmington: by Dr. G. F. Kunz.
1891-1903: Barratta and Thunda: by Prof. A. Liversidge,
F.R.S.
1894: Makariwa: by Prof. G. H. F. Ulrich.
1894: Bherai: by the Nawab of Junagadh, India.
1895: Concepcion: by Mr. W. Taylor.
1896: Madrid: by Don Miguel Merino of Madrid.
1897: Cold Bokkeveld: by Mrs. Whitwell.
1899, 1906: Caperr: by the Director of the La Plata Museum.
1899: El Ranchito (Bacubirito): by Mr. O. H. Howarth.
1899: Kokstad: by the Trustees of the South African Museum.
1899: Zomba: by Sir A. Sharpe, C.B., K.C.M.G., Mr. J. F. Cunningham, and Mr. J. McClounie.
1901: Ness City: by Dr. H. A. Ward.
1903: Caratash: by His Highness Kiamil Pasha.
1904: Narraburra: by Mr. H. C. Russell, C.M.G., F.R.S.
1905: Fukutomi, Oshima, Tanakami and Yonõzu: by Dr. C. Ishikowa.
1905: Kota-Kota: by Mr. A. J. Swann.
1907: Kangra: by Prof. W. N. Hartley, F.R.S.
1908: Uwet: by the Governor of Southern Nigeria.
Since the same year (1863) meteoritic exchanges have
been made with the museums of Belgrade, Berlin, Blömfontein,
Breslau, Calcutta, Calne, Cambridge, Chicago (Field
Columbian Museum), Christiania, Debreczin, Dresden, Fremantle,
Göttingen, Helsingfors, Munich, Odessa, Paris, Pau,
Rio de Janeiro, Rome, St. Petersburg (Institute of Mines),
South Africa, Stockholm, Sydney, Transylvania, Troyes,
Utrecht, Vienna, Washington, Wisconsin University, and
Yale College; and also with the following:—Dr. Abich of
Dorpat, Dr. J. Auerbach of Moscow, Mr. S. C. H. Bailey of
Cortlandt-on-Hudson, U.S.A., Prof. Baumhauer of Haarlem,
Mr. C. S. Bement of Philadelphia, U.S.A., Dr. Breithaupt
of Freiberg, Dr. A. Brezina of Vienna, Mr. J. B. Gregory
of London, Prof. C. T. Jackson of Boston, U.S.A., Mr.
Henry Ludlam of London, Prof. W. Mallet of Virginia,
U.S.A., Prof. Vom Rath of Bonn, Prof. C. U. Shepard of
New Haven, U.S.A., His Excellency Julien de Siemachko
of St. Petersburg, Prof. Lawrence Smith of Louisville,
U.S.A., Mr. J. N. Tilden of New York, U.S.A., and Dr.
Henry A. Ward of Chicago, U.S.A.
In this way, by the generosity and self-denial of donors,
by the somewhat difficult method of exchange, and by
purchase, it has been possible to get together the fine
representative collection of meteorites now in the British
Museum.
AN INTRODUCTION
TO THE
STUDY OF METEORITES.
Most of the specimens here referred to are in Case 4 in the Pavilion at the
end of the Mineral Gallery.
The fall of stones from the sky formerly discredited.
1. Till the beginning of the nineteenth century, the fall
of stones from the sky was an event, the actuality of which
neither men of science nor people in general could be
brought to credit. Yet such falls have been recorded
from the earliest times, and the records have occasionally
been received as authentic by a whole nation. In most cases,
however, the witnesses of such an event have been treated
with the disrespect usually shown to reporters of the extraordinary,
and have been laughed at for their supposed delusions:
this is less to be wondered at when we remember
that the witnesses of the arrival of a stone from the sky have
usually been few in number, unaccustomed to exact observation,
frightened both by what they saw and by what they
heard, and have had a common tendency towards exaggeration
and superstition.
Ancient records.
2. De Guignes in his Travels states that, according to old
Chinese manuscripts, falls of stones have again and again
been observed in China; the earliest mentioned is one
which happened about 644 B.C.
A stone, famous through long ages,1
fell in Phrygia and
was preserved there for many generations. About 204 B.C.
it was demanded from King Attalus and taken with great
ceremony to Rome. It is described as "a black stone,
in the figure of a cone, circular below and ending in
an apex above."
In his History of Rome, Livy tells of a shower of stones
on the Alban Mount, about 652 B.C., which so impressed the
Senate that a nine days' solemn festival was decreed; as the
shower lasted for two days, it was doubtless the result of
volcanic action; other instances of the "rain of stones" in
Italy, mentioned by the same author, had possibly a similar
origin.
Plutarch relates the fall of a stone in Thrace about 470
B.C., during the time of Pindar, and according to Pliny, the
stone was still preserved in his day, 500 years afterwards.
The latter records two other falls, one in Asia Minor, the
other in Macedonia.
Worship of meteoric stones.
3. These falls from the sky, when credited at all, have
been deemed prodigies or miracles, and the stones have been
regarded as objects for reverence and worship. It has even
been conjectured that the worship of such stones was the
earliest form of idolatry. The Phrygian stone, mentioned
above, was worshipped at Pessinus by the Phrygians and
Phœnicians as Cybele, "the mother of the gods," and its
transference to Rome followed the announcement by an
oracle that possession of the stone would secure to the
State a continual increase of prosperity. Similarly, the
Diana of the Ephesians, "which fell down from Jupiter,"
and the image of Venus at Cyprus, appear to have been,
not statues, but conical or pyramidal stones. A stone,
of which the history goes back far beyond the seventh century,
is still revered by the Moslems as one of their holiest
relics, and is preserved at Mecca built into the northeastern
corner of the Kaaba. The late Paul Partsch,2 for
many years Keeper of Minerals in the Imperial Museum
of Vienna, considered that the meteoric origin of the Kaaba
stone was sufficiently proved by descriptions which had
been submitted to him. A stone which fell in Japan in
Pane 4c.
the year 1741, and was presented to the British Museum
in 1883, had long been made an annual offering in a temple
of Ogi at one of the Japanese religious festivals. It may
be added that a stone which lately fell in India3 was
decked with flowers, daily anointed with ghee (clarified
butter), and subjected to frequent ceremonial worship and
coatings of sandal-wood powder. The stone was placed on
a terrace constructed for it at the place where it struck the
ground, and a subscription was made for the erection of a
shrine.
The oldest undoubted meteoric stone still preserved.
Pane 4c.
4. The oldest undoubted sky-stone still preserved is that
which was long suspended by a chain from the vault of the
choir of the parish church of Ensisheim in Elsass, and is
now kept in the Rathhaus of that town. The following is a
translated extract from a document which was preserved
in the church:—
"On the 16th of November, 1492, a singular miracle
happened: for between 11 and 12 in the forenoon,
with a loud crash of thunder and a prolonged noise
heard afar off, there fell in the town of Ensisheim a
stone weighing 260 pounds. It was seen by a child
to strike the ground in a field near the canton called
Gisgaud, where it made a hole more than five feet
deep. It was taken to the church as being a
miraculous object. The noise was heard so distinctly
at Lucerne, Villing, and many other places, that in
each of them it was thought that some houses had
fallen. King Maximilian, who was then at Ensisheim,
had the stone carried to the castle: after breaking
off two pieces, one for the Duke Sigismund of Austria
and the other for himself, he forbade further damage,
and ordered the stone to be suspended in the parish
church."
Scientific men begin to investigate the reports.
5. Three French Academicians, one of whom was the
afterwards renowned chemist Lavoisier, presented to the
Academy in 1772 a report on the analysis of a stone said to
have been seen to fall at Lucé on September 13, 1768. As
Pane 4c.
the identity of lightning with the electric spark had been
recently established by Franklin, they were in advance
convinced that "thunder-stones" existed only in the
imagination; and never dreaming of the existence of a
"sky-stone" which had no relation to a "thunder-stone," they
somewhat easily assured both themselves and the Academy
that there was nothing unusual in the mineralogical
characters of the Lucé specimen, their verdict being that
the stone was an ordinary one which had been struck and
altered by lightning.
Chladni argues that the bodies come from outer space.
6. In 1794 the German philosopher Chladni, famed for
his researches into the laws of sound, brought together
numerous accounts of the fall of bodies from the sky, and
called the attention of the scientific world to the fact that
several masses of iron, of which he specially considers two,
had in all probability come from outer space to this planet.4
The Pallas iron.
Pane 4c.
One of them is the mass still known as the Pallas or
Krasnojarsk iron.5 This irregular mass, weighing about
1500 lbs., of which the greater part is in the Museum
at St. Petersburg, was met with at Krasnojarsk by the
traveller Pallas in the year 1772, and had been found in
1749 by a Cossack on the surface of the highest part of a
lofty mountain between Krasnojarsk and Abakansk in
Siberia, in the midst of a schistose district: it was regarded
by the Tartars as a "holy thing fallen from heaven." The
interior is composed of a ductile iron, which, though brittle
at a high temperature, can be forged either cold or at a
moderate heat; its large sponge-like pores are filled with
an amber-coloured olivine; the texture is uniform, and the
olivine equally distributed; a vitreous varnish had preserved
it from rust. The fragment in the case, weighing about
7 lbs., was presented to the Trustees in 1776 by the Academy
of Sciences of St. Petersburg.
The Otumpa iron.
Separate stand.
A second specimen referred to is that which in 1783 Don
Michael Rubin de Celis was sent by the Viceroy of Rio de la
Plata to investigate;6 it had been found by Indians, searching
for honey and wax, and trusting to rain for drink,
projecting about a foot above the ground near a place called
Otumpa, in the Gran Chaco Gualamba, South America, and
was at first thought to be the outcrop of an iron vein.
Don Rubin de Celis estimated the weight of this mass of
malleable iron at thirty thousand pounds, and reported that
for a hundred leagues around there were neither iron mines
nor mountains nor even the smallest stones, and that owing
to the absence of water, there was not a single fixed habitation
in the country. There were several smaller masses at
the locality; one of them, weighing 1400 lbs., is shown on a
separate stand in the Pavilion: according to Sir Woodbine
Parish, who presented it to the Museum in 1826, it had been
removed to Buenos Ayres at the beginning of the struggle for
Independence; it was a complimentary gift to Sir Woodbine
on the occasion of his being sent by Canning to acknowledge
the Independence of the State. Pane 4c.A slice of this iron is shown
in case 4c.
Chladni's arguments.
7. Chladni argued that these masses could not have been
formed in the wet way, for they had evidently been exposed
to fire and slowly cooled: that the absence of scoriæ in the
neighbourhood, the extremely hard and pitted crust, the
ductility of the iron, and, in the case of the Siberian mass,
the regular distribution of the pores and olivine, precluded
the idea that they could have been formed where found,
whether by man, electricity, or an accidental conflagration:
he was driven to conclude that they had been formed elsewhere,
and projected thence to the places where they were
discovered; and as no volcanoes had been known to eject
masses of iron, and as, moreover, no volcanoes are met with
in those regions, he held that the specimens referred to
must have actually fallen from the sky. Further, he sought
to show that the flight of a heavy body through the sky is the
direct cause of the luminous phenomenon known as a fire-ball.
The fall of stones at Siena, in Tuscany.
Pane 4c.
8. About seven o'clock on the evening of June 16, 1794,
as if to direct attention to Chladni's just published theory,
there fell a shower of stones at Siena, in Tuscany.
The event is described in the following letter, dated
Siena, July 12, 1794, from the Earl of Bristol to Sir
William Hamilton, K.B., F.R.S., at that time British Envoy-Extraordinary
and Plenipotentiary at the Court of
Naples:—7
"In the midst of a most violent thunderstorm, about a
dozen stones of various weights and dimensions fell
at the feet of different persons, men, women and
children. The stones are of a quality not found in
any part of the Siennese territory; they fell about
18 hours after the enormous eruption of Mount
Vesuvius: which circumstance leaves a choice of
difficulties in the solution of this extraordinary phenomenon.
Either these stones have been generated
in this igneous mass of clouds which produced such
unusual thunder, or, which is equally incredible,
they were thrown from Vesuvius, at a distance of at
least 250 miles: judge, then, of its parabola. The
philosophers here incline to the first solution. I
wish much, Sir, to know your sentiments. My first
objection was to the fact itself, but of this there are
so many eyewitnesses, it seems impossible to withstand
their evidence."
The fall of a stone near Wold Cottage, Yorkshire.
Pane 4b.
9. Soon afterwards there fell a stone in England itself.
About three o'clock in the afternoon of December 13, 1795,
a labourer working near Wold Cottage, a few miles from
Scarborough, in Yorkshire,8 was terrified to see a stone fall
about ten yards from where he was standing. The stone,
weighing 56 lbs., was found to have gone through 12 inches
of soil and 6 inches of solid chalk rock. No thunder,
lightning, or luminous meteor accompanied the fall; but in
the adjacent villages there was heard an explosion likened
by the inhabitants to the firing of guns at sea, while in two
of them the sounds were so distinct of something singular
passing through the air towards Wold Cottage, that five or
six people went to see if anything extraordinary had
happened to the house or grounds. No stone presenting
Pane 4b.
the same characters was known in the district. The stone
is preserved in the Museum Collection.
Terrestrial origin still sought for.
10. It seemed to be now impossible for any one to doubt
the fall of stones from the sky, but the reluctance of
scientific men to grant an extra-terrestrial origin to them is
shown by the theories referred to in the above letter to Sir
William Hamilton, and is rendered even more evident by the
theory proposed in 1796 by Edward King, who suggested
that the stones had their origin in the condensation of a
cloud of ashes, mixed with pyritical dust and numerous
particles of iron, coming from some volcano. As the stones
fell at Siena out of a cloud coming from the North, while
Vesuvius is really to the South, he gravely suggested that
in this case the cloud had been blown from the South past
Siena, and had then before its condensation into stone been
brought back by a change of wind. As to the fall of a stone
near Wold Cottage, he was not prepared either to believe or
disbelieve the witnesses until the matter had been more
closely examined; but in case the statements should prove
worthy of credit, he points out the possibility of the
necessary dust-cloud having come from Mount Hecla in
Iceland.
The fall of stones near Benares, in India.
Pane 4c.
11. Later came a well-authenticated account of a more
wonderful event still. At 8 o'clock on the evening of
December 19, 1798, many stones fell at Krakhut, 14 miles
from Benares, in India; the sky was perfectly serene, not a
cloud had been seen since December 11, and none was
seen for many days after. According to the observations of
several Europeans, as well as natives, in different parts of
the country, the fall of the stones was preceded by the
appearance of a ball of fire, which lasted for only a few
instants, and was followed by an explosion resembling
thunder.
Examination of stones by Howard.
12. Fragments of the stones of Siena, Wold Cottage, and
Krakhut, as also of a stone said to have fallen on July 3,
1753, at Tabor, in Bohemia, came into the hands of Edward
Howard, and the comparative results of a chemical and
mineralogical investigation (the latter by the Count de
Bournon) of the stones from the above four places are
given in a paper read before the Royal Society of London,
on February 25, 1802. Howard concludes as follows:—
Pane 4c.
"The mineralogical descriptions of the Lucé stone by the
French Academicians, of the Ensisheim stone by M.
Barthold, and of stones from the above four places
(Siena, Wold Cottage, Krakhut and Tabor) by the
Count de Bournon, all exhibit a striking conformity
of character common to each of them, and I doubt
not but the similarity of component parts, especially
of the malleable alloy, together with the near
approach of the constituent proportions of the earth
contained in each of the four stones, will establish
very strong evidence in favour of the assertion that
they have fallen on our globe. They have been
found at places very remote from each other, and at
periods also sufficiently distant. The mineralogists
who have examined them agree that they have no
resemblance to mineral substances properly so called,
nor have they been described by mineralogical
authors."
Could projectiles reach the earth from the moon?
13. This paper aroused much interest in the scientific
world, and, though Chladni's view that such stones come
from outer space was still not generally accepted in France,
it was there deemed more worthy of consideration after
Poisson9 (following Laplace) had shown that a body shot from
the moon in the direction of the earth, with an initial velocity
of 7592 feet a second, would not fall back upon the moon,
but would actually, after a journey of sixty-four hours, reach
the earth, upon which, neglecting the resistance of the air,
it would fall with a velocity of about 31,508 feet a second.
The fall of stones at L'Aigle, in France.
14. Whilst the minds of the scientific men of France were
in this unsettled condition, there came a report that still
another shower of stones had fallen, this time in their own
Pane 4c.
country, and within easy reach of Paris. To settle the matter
finally, if possible, the physicist Biot, Member of the French
Academy, was directed by the Minister of the Interior to
inquire into the event upon the spot. After a careful
examination of the stones and a comparison of the statements
of the villagers, Biot10 was convinced that—
1. On Tuesday, April 26, 1803, about 1 P.M., there was
a noise as of a violent explosion in the neighbourhood
of L'Aigle, in the department of Orne, followed by a
rolling sound which lasted for five or six minutes:
the noise was heard for a distance of 75 miles round.
2. Some moments before the explosion at L'Aigle, a fire-ball
in quick motion was seen from several of the
adjoining towns, though not from L'Aigle itself.
3. There was absolutely no doubt that on the same day
many stones fell in the neighbourhood of L'Aigle.
Biot estimated the number of the stones at two or three
thousand; they fell within an ellipse of which the larger axis
was 6·2 miles, and the smaller 2·5 miles; and this inequality
might indicate not a single explosion but a series of them.
With the exception of a few little clouds of ordinary character,
the sky was quite clear.
The exhaustive report of Biot, and the completeness
of his proofs, compelled the whole of the scientific world to
recognise the fall of stones on the earth from outer space as
an undoubted fact.
The times and places of fall are independent of terrestrial circumstances.
15. Since that date many falls have been observed, and the
attendant phenomena have been carefully investigated. These
observations teach us that meteorites, as they are now called,
fall at all times of the day and night, and at all seasons of
the year, while they favour no particular latitudes: also
they are found to be quite independent of the weather, and
in many cases have fallen when the sky has been perfectly
clear; even where stones have fallen in what has been called
a thunder-storm, we may reasonably suppose that in most
cases the luminous phenomenon has been mistaken for a
variety of lightning, and the loud noise for thunder.
Velocity of meteorites.
16. From observations of the path and the time of flight
of the luminous meteor, it is calculated that meteorites enter
the earth's atmosphere with absolute velocities ranging
from 10 to 45 miles a second: the velocity actually observed
is that relative to a person at rest on the earth's surface;
for the determination of the absolute velocity of the
meteorite, the motion of the observer with the earth (about
18 miles a second) must be allowed for. Let us attempt
to follow the course of a small compact body moving at
such a rate. So long as the body is traversing "empty
space," the only heat it receives is that sent direct from
the sun and stars; in general, the meteorite will thus be
probably very cold, and, owing to its small size and
want of luminosity, it will be invisible to an observer
on the earth's surface. After the meteorite enters the
earth's atmosphere a very speedy change must take place.
The resistance of the air.
Assuming the law of resistance of the air for a planetary
velocity to be the same as that deduced from experiments
with artillery, the astronomer Schiaparelli11 has shown that
if a ball of 8 inches diameter and 32-1/3 lbs. weight enter the
atmosphere with a velocity of 44¾ miles a second, its velocity
on arriving at a point where the barometric pressure is still
only 1/760th of that at the earth's surface will have been
already reduced to 3-1/6 miles a second. From this it is clear
that the speed of the meteorite after the whole of the
atmosphere has been traversed will be extremely small, and
comparable with that of an ordinary falling body. From
experiments made by Professor A. S. Herschel, it has been
calculated that the velocity of the meteorite which fell
at Middlesbrough, in Yorkshire, on March 14, 1881, was,
on striking the ground, only 412 feet a second. From the
depth of the hole (20 to 24 inches) made in stiff loam by
the stone which fell at Hvittis, in Finland, on October 21,
1901, it has been estimated by Mr. Borgström that the
meteorite had a velocity of 584 feet a second when it
reached the earth. He further calculates that the stone
would have acquired virtually the same velocity if it had
been merely allowed to fall, from a position of rest, under
the action of gravity, through an infinite atmosphere having
the same density as at the earth's surface. In the case of the
Hessle fall, several stones fell on the ice, which was only a
few inches thick, and rebounded without either breaking
the ice or being broken themselves.
Transformation of the energy.
17. Further, Schiaparelli pointed out that, in the case
imagined by him, the energy already converted into heat
would be sufficient to raise 198,400 pounds of water from
freezing point to boiling point under the ordinary barometric
pressure. The greater part of this heat is, no doubt, carried
off by the air through which the meteorite passes; but
still the wonder is, not that a meteorite is small on
reaching the earth's surface, but that any of it is left to
"tell the tale."
The cloud, ball of fire and trail.
This sudden generation of heat will cause fusion, and even
luminosity, of the outer material of the meteorite, and in
some cases a combustion of some of its constituents: the
products of the thermal and mechanical action sufficiently
account for the cloud from which the meteorite is generally
seen to emerge as a ball of fire, and also for the visible
trail often left behind. The ball of fire has often an
apparent diameter larger even than that of the moon, and
is sometimes too bright for the eye to gaze upon.
The meteorite is only luminous in the first part of its flight through the air.
18. Owing to the quick reduction of speed, the luminosity
will be a feature of the higher, not the lower, part of the
course. The Orgueil meteorite of May 14, 1864, was so
high when luminous that, notwithstanding its almost
easterly motion, it was seen over a space of country
ranging from the Pyrenees to the north of Paris, a distance
of more than 300 miles.
The time of flight through the air is very brief.
19. Next we may remark that the time of flight in the
earth's atmosphere will be very short, and reckoned only by
seconds. Even when the meteorite is wholly metallic, if we
may judge from the time one end of a poker may be held in
the hand whilst the other end is in the fire, the heat will not
have had time to get far below the surface before the body
Pane 4d.
will have reached the ground.
The crust.
As a matter of fact, meteorites are almost invariably
found to be covered with a crust or varnish, such as would
be caused by strong heating, and its thinness shows the
slight depth to which the heat has had time to penetrate;
in the case of the stones, the greater part of the suddenly
heated superficial material must chip off and be left behind
at all parts of the track of the meteor. The aspect of the
crust varies according to the mineral constitution of the
meteorites: it is generally black, and in most cases dull, as
Pane 4d.
in High Possil, Zsadány and Orgueil, but sometimes shiny,
as in Stannern, or partly dull and partly shiny, as in
Dyalpur; rarely, it is of a dark grey colour, as in Mezö-Madaras
and some of the stones which fell in the neighbourhood
of Mocs. In the case of the Pultusk meteorite of
Panes 4efg.
January 30, 1868, several thousands of stones, varying
from the size of a man's head to that of a small nut, were
picked up, each covered with a crust: fifty-six of the stones
of this fall are shown in the case.
20. The crust is not of equal thickness at every point; for,
the form of the meteorite being a result of oft-repeated fracture,
the constantly changing surface must be very irregular,
and its different parts must be heated to different temperatures
and be exposed to different amounts of mechanical action.
Sometimes, owing to the motion of the meteorite through
the air, the crust is so marked as to indicate the position of
the meteorite in regard to its line of motion at a certain
part of its course; and this relation is rendered more clear
in some cases by evidence that melted material has been
driven to the back of the moving mass. The Nedagolla iron
Pane 4h.
and the Goalpara stone illustrate this peculiarity.
The pittings.
21. Further, the surface of a meteorite is generally
covered with pittings, which have been compared in form to
thumb-marks: stones from the Supuhee, Futtehpur, and
Pane 4h.
Knyahinya falls present good examples of this character.
It is remarkable that pittings bearing a close resemblance
to those of meteorites have been observed on the large
partially burned grains of gunpowder, which have been
Pane 4h.
picked up near the muzzle after the firing of the 35-ton and
80-ton guns at Woolwich. The pitting of the gunpowder
grains is attributed to unequal combustion, but that of
meteorites seems to be due not so much to inequality of
combustibility as to that of conductivity, fusibility and
frangibility of the matter at the surface.
Fragmentary form of meteorites.
22. As picked up, complete and covered with crust,
meteorites are not spherical, nor have they any definite
shape: in fact, they are always irregular angular fragments,
such as would be obtained on breaking up a rock presenting
no regularity of structure.
In the case of the Butsura fall of May 12, 1861,12 fragments
of the stone were picked up three or four miles
apart, and, wonderful to say, it was possible to reconstruct
Pane 4h.
with much certainty the portion of the meteorite to which
they once belonged: a model of the reconstructed portion is
Pane 4a.
shown in the case. Two of the fragments, in other respects
fitting perfectly together, are even on the faces of the
junction now coated with a black crust, showing that one
disruption took place when the meteorite had a high velocity;
two other fragments found some miles apart fitted
perfectly, and were neither of them incrusted at the surface
of fracture, thus indicating another disruption at a time
when the velocity of the meteorite had been so far reduced
that the material of the new faces was not blackened through
the generation of heat. Sometimes, as in the case of the
meteorite of Orgueil, the fragments reach the ground before
the detonation is heard, proving that the fracture has taken
place at a part of the course where the velocity of the
meteorite was considerably greater than that of the sound-vibrations
(1100 feet a second).
The detonations.
23. The sudden condensation of air in front of the
meteorite, the consequent generation of heat and expansion
of the outer shell, have been held to account not only for
the break-up of the meteorite into fragments, but partly
also for the crash like that of thunder which is a usual
accompaniment of the fall. Others have referred this noise
solely to the sudden rush of air into the space traversed
by the meteorite in the early part of the course. It has,
however, now been discovered that the mere flight of a
projectile through the air with a velocity exceeding that
of sound (1100 feet a second) is itself sufficient to cause a
loud detonation; neither explosion, like that of a bomb-shell,
nor simple fracture of the meteorite by reason of pressure
or sudden heat, is a necessary preliminary to the production
of the loud noise. It is found, in fact, that when a projectile
is fired with high initial velocity, say 2350 feet a second, an
observer near the path of the projectile begins to distinguish
two detonations as soon as his distance from the cannon
reaches 500 feet; the first of them, a sharp one, appears to
come from that part of the projectile's path which is nearest
to the observer, and travels with the velocity of the projectile;
the later and duller one appears to come from the cannon
itself, and travels with the velocity of sound. If the projectile
is intercepted near the cannon, only a single detonation
is heard by an observer in the same position as before,
and it travels at the rate of 1100 feet a second. If the initial
velocity of the projectile is less than that of sound, only a
single detonation is heard, and it starts from the cannon.
The rolling sound, which follows the detonation of a
meteorite, is due, as in the case of thunder, to echoes from
the ground and the clouds.
The detonations due to the different members of a swarm
of meteorites will combine to form a single detonation
unless they are separated by perceptible intervals of time.
The sounds heard after the loud detonations.
24. After the detonation, sounds are generally heard which
have been variously likened to the flapping of the wings of
wild geese, the bellowing of oxen, Turkish music, the roaring
of a fire in a chimney, the noise of a carriage on the
pavement, and the tearing of calico: these sounds are probably
due to the whirling and oscillation of the fragments
while traversing the air, with small velocity, near the
observers, and correspond to the hiss or hum observed in
the case of a projectile travelling with a velocity less than
that of sound.
The chemical elements found in meteorites.
25. As to the kinds of elementary matter13 of which
meteorites are composed, about one-third, and those the
most common, of the elements at present recognised as
constituents of the earth's crust have been met with: no
new elementary body has been discovered.
The most frequent or plentiful in their occurrence are:—
- Aluminium
- Calcium
- Carbon
- Iron
- Magnesium
- Nickel
- Oxygen
- Phosphorus
- Silicon
- Sulphur:
while, less frequently or in smaller quantities, are found:
- Antimony
- Arsenic
- Chlorine
- Chromium
- Cobalt
- Copper
- Hydrogen
- Lithium
- Manganese
- Nitrogen
- Potassium
- Sodium
- Strontium
- Tin
- Titanium
- Vanadium.
Elements present only in minute quantity.
26. In addition to the above, the existence of minute traces
of several other elements has been announced; of these special
mention may be made of gallium, gold, iridium, lead,
platinum and silver.
Both simple and combined.
27. Most of the above elements are present in the combined
state; the iron occurring chiefly in combination with nickel,
and the phosphorus almost always combined with both nickel
and iron. Some of them are found also in their elementary
condition: perhaps hydrogen and nitrogen; carbon, both as
indistinctly crystallised diamond and as graphitic carbon,
the latter being generally amorphous, but occasionally in
cubic crystals (cliftonite); free phosphorus has been found
in Saline Township; free sulphur has been observed in one of
the carbonaceous meteorites, but may have been separated from
the unstable sulphides since the entry into our atmosphere.
Some of the constituents are new to mineralogy.
Pane 4k.
28. Of the constituents of meteorites, the following are
by many mineralogists regarded as being at present
unrepresented among the terrestrial minerals:—
Cliftonite, a cubic form of graphitic carbon,
Phosphorus,
Various alloys of nickel and iron,
Moissanite, silicide of carbon,
Cohenite, carbide of iron and nickel; corresponding to
Cementite, carbide of iron, found in artificial iron,
Schreibersite, phosphide of iron and nickel,
Troilite, proto-sulphide of iron,
Oldhamite, sulphide of calcium,
Osbornite, oxy-sulphide of calcium and titanium or
zirconium,
Daubréelite, sulphide of iron and chromium,
Lawrencite, protochloride of iron,
Asmanite, a species of silica,
Maskelynite, a singly refracting mineral with the composition
of labradorite.
Weinbergerite, silicate intermediate in chemical composition
between pyroxene and nepheline.
Nature of troilite, asmanite and maskelynite.
Of the above, Troilite is perhaps identical with some
varieties of terrestrial pyrrhotite: Asmanite, the form of silica
obtained in 1867 by Prof. Maskelyne from the Breitenbach
meteorite, was announced by him in 1869 to be optically
biaxal, and thus to belong to a crystalline system different
from the hexagonal to which both tridymite, then just
announced by Vom Rath, and quartz had been assigned.
Later investigations of tridymite have shown that its optical
characters and crystalline form are inconsistent with the
hexagonal system of crystallisation, and it is not impossible
that asmanite and tridymite may be specifically identical.
It has been found that tridymite becomes optically uniaxal
at a moderate temperature, and its general characters appear
to be essentially identical with those of asmanite. According
to one view, Maskelynite is the result of fusion of a plagioclastic
felspar; according to another, it is an independent
species chemically related to leucite.
Compounds identical with terrestrial minerals.
Pane 4k.
29. Other compounds are present, corresponding to the
following terrestrial minerals:—
Olivine and forsterite,
Enstatite and bronzite,
Diopside and augite,
Anorthite, labradorite and oligoclase,
Leucite,
Magnetite and chromite,
Pyrites,
Pyrrhotite,
Breunnerite.
Further, from one of the Lancé stones, chloride of sodium,
and from the carbonaceous meteorites, sulphates of sodium,
calcium and magnesium, have been extracted by means of
water.
In addition to the above, there are several compounds or
mixtures of which the nature has not yet been satisfactorily
ascertained.
The rarity of quartz.
30. Quartz, the most common of terrestrial minerals, is
absent from the stony meteorites; but in the undissolved
residue of the Toluca iron microscopic crystals have been
found, some of which have important characters identical
with those of quartz, while others resemble zircon. As
mentioned above, free silica is present in the Breitenbach
meteorite as asmanite.
The conditions under which these compounds can have been formed.
31. As to the conditions14 under which such compounds
can have been formed, we may assert that they must have
been very different from those which at present obtain near
the earth's surface: in fact, it is impossible to imagine that
phosphorus, the metallic nickel-iron and the unstable sulphides
can either have been formed, or have remained unaltered,
under circumstances in which water and atmospheric air have
played any prominent part. Still, what little we do know
of the inner part of our globe does not shut out the possibility
of the existence of similar elementary and compound
bodies at great depths below the surface. Daubrée,15 after
experiment, inclines to the belief that the iron is due, in
many cases at least, to reduction from an olivine rich in
diferrous silicates, and this view perhaps acquires some
additional probability from the fact that hydrogen and
carbonic oxide are given off when meteoric iron is heated:
the existence, however, of such siderolites as that of Krasnojarsk,
which is rich both in metallic iron and in
orthosilicate of iron and magnesium (olivine), and yet presents
no traces of the intermediate metasilicate of iron and
magnesium (bronzite), offers a weighty objection to the
general application of this view.
Classification.
32. Meteorites may be conveniently arranged in three
classes, which pass more or less gradually into each other:
the first includes all those which consist mainly of iron, and
have, therefore, been called by Prof. Maskelyne aero-siderites
(aer, air, and sideros, iron), or, more shortly, Siderites; the
second is formed by those which are composed chiefly of iron
and stone, both in large proportion, and are called aero-siderolites,
or, shortly, Siderolites; while those of the third
class, being almost wholly of stone, are called Aerolites (aer,
air, and lithos, stone).
The siderites.
33. In the Siderites the iron generally varies from 80 to
95 per cent., and the nickel from 6 to 10 per cent.; in the
Santa Catharina siderite (of which the meteoric origin is
somewhat doubtful) 34, and in that of Oktibbeha County
60, per cent. of nickel have been found: the nickel is alloyed
with the iron, and several of the alloys have been distinguished
by special names. Owing to the presence of the
nickel, meteoric iron is often so white on a fractured surface
as to be mistaken for silver by its finder; it is also less
liable to rust than ordinary iron is. Troilite is frequently
present as plates, veins or large nodules, sometimes surrounded
by graphite; schreibersite is almost always found,
and occasionally also daubréelite.
Evolution of gases on heating.
Further, various chemists have proved that hydrogen,
nitrogen, marsh gas, and the carbonic oxides are evolved
when meteoric iron or stone is heated; in one case a trace
of helium was detected. Probably the gases were not
present in the occluded state, but resulted from the decomposition
or interaction of non-gaseous constituents during
the experiments.
Pane 4l.
Figures produced by action of acids or bromine.
Etched figures.
34. The want of homogeneity and the structure of
meteoric iron are beautifully shown by the figures generally
called into existence when a polished surface is exposed to
the action of acids or bromine; they are due to the inequality
of the action on thick or thin plates of various
constituents, the plates being composed chiefly of two nickel-iron
materials termed kamacite and tænite. A third nickel-iron
material, filling up the spaces formed by the intersection
of these plates of kamacite and tænite, is termed plessite; it
is probably not an independent substance but an intergrowth
of the first two kinds.
In the Agram iron, investigated by Widmanstätten in
1808, the plates are parallel to the faces of the regular
octahedron; such figures are well shown by the exhibited
slice of the Toluca iron; different degrees of distinctness of
such "Widmanstätten" figures are illustrated by specimens
Pane 4l.
of Seneca River, Zacatecas, Charcas, Burlington, Jewell Hill,
Lagrange, Victoria West, Nelson County, and Seeläsgen.
The large Otumpa specimen, mounted on a separate pedestal,
furnishes a good example of the less distinct, and more or
less damascene, appearance presented by the etched surface
of some meteoric irons of octahedral structure.
The Braunau iron gives no "Widmanstätten" figures, but
has cleavages parallel to the faces of a cube; on etching it
yields linear furrows which were found (1848) by Neumann
to have directions such as would result from twinning of
the cube about an octahedral face; as illustrations of the
"Neumann lines," etched specimens of Braunau and Salt
Pane 4l.
River are exhibited.
For meteoric irons of cubic structure the percentage of
nickel is lower than 6 or 7; for those of octahedral structure
it is higher than 6 or 7, and the plates of kamacite are
thinner, and the structure therefore finer, the higher the
percentage of that metal. A considerable number of
meteoric irons, however, show no crystalline structure at
all, and have percentages of nickel both below and above 7;
it has been suggested that these masses have been metamorphosed,
and that crystalline structure was once present, but
has disappeared as a result of the meteorites having been
heated, not merely superficially during their passage through
the earth's atmosphere, but throughout their mass while
travelling in outer space.
Cooling of fused mixtures and of solutions.
35. Though meteoric iron has been at some time, presumably,
in a state of fusion, and its present structure is a result
of the particular circumstances of the cooling of the liquid
and afterwards solid material, attempts to produce such
structures by the cooling of fused meteoric iron or artificial
mixtures of nickel and iron have not yet been successful.
It will be useful, therefore, to consider briefly some of the
manifold changes which are found to take place during the
passage of fused mixtures and of solutions to the solid
state, and during the cooling of such solids to ordinary
temperatures.
If a fused mixture of antimony and bismuth is allowed to
cool, the solid which first separates is neither pure antimony
nor pure bismuth, but a material which has a percentage
composition depending on, though not identical with, that
of the original mixture. The temperature for the beginning
of the solidification is different for different proportions of
the two metals, and is intermediate between 622° and 268°,
the solidifying temperatures of antimony and bismuth,
respectively; it approaches the latter more and more
closely as the percentage of the bismuth is increased. The
solid first separated is somewhat richer in antimony than
the original mixture; the still fused part, therefore, is
somewhat richer in bismuth than before, and does not begin
to solidify till a lower temperature is reached; the temperature
thus gradually falls, instead of remaining constant,
during the solidification. In the cooling of such fused
mixtures the changing composition of the part still fused
has for effect a changing composition of the solid already
separated; whence the slower the cooling of the fused
material, the greater is the homogeneity of the final
solid.
Eutectic mixtures.
A fused mixture of silver and copper behaves in a different
way. When the percentage weight of the silver is 72, and
that of the copper, therefore, is 28, solidification begins, not
at a temperature between 960° and 1083°, the solidifying
temperatures of silver and copper, respectively, but at a
temperature below both, namely, 770°. The solid which
first separates has the same percentage composition as the
original mixture; the part still fused has thus itself the
same percentage composition as before, and continues to
Cooling of fused mixtures and of solutions.
solidify at the same temperature, and in the same way, until
the solidification is complete. Such a mixture, having a
definite composition and a definite temperature of solidification,
was for a time regarded as a definite chemical compound
with a complex chemical formula, but on microscopic
examination the resultant solid is found to be heterogeneous;
minute particles of the silver and copper are seen to lie side
by side, the particles being granular or lamellar in form
according to the circumstances of the cooling. If the percentage
of silver is different from 72, whether it be higher
or lower, the solidification begins at a higher temperature
than 770°; whence the mixture containing 72 per cent.
of silver has been conveniently termed eutectic (i.e. very
fusible); the term was suggested by Prof. F. Guthrie,16 to
whom our knowledge of the existence of such mixtures is due.
36. When the silver is in excess of 72 per cent., the excess
of silver gradually collects together and solidifies at various
parts of the cooling fused mass; the still fused portion thus
gradually becomes poorer in that metal, and the temperature,
instead of remaining constant, gradually falls during the
separation of the solid. At length the percentage of silver
in the fused portion falls to 72 per cent. and the temperature
to 770°; the solid which now begins to form is no longer
pure silver, but a material containing 72 per cent. of that
metal; and it continues to have the same percentage composition
as the surrounding liquid, and the temperature of solid
and liquid to be 770°, until the solidification is complete.
The final solid thus consists of blebs of silver scattered
through a fine groundmass of eutectic mixture of silver and
copper. Similarly, if the copper is in excess of 28 per cent.,
the final solid consists of blebs of copper scattered through
a fine groundmass of eutectic mixture of silver and copper.
If the two metals are copper and antimony, instead of
copper and silver, the results are more complicated; for the
first two metals are capable of combining together to form
a definite chemical compound represented by the formula
Cu2Sb, and each of the metals forms a eutectic mixture with
the latter. According to the percentage composition of the
original mixture, the solid which first separates during
cooling from fusion may be either copper or antimony or
the compound Cu2Sb; the separation continuing, and the
temperature falling, until the first eutectic proportion and
its corresponding temperature are reached.
Cooling of solutions.
37. Analogous results are obtained during the cooling of
solutions; for instance, during the cooling of a solution of
sodium chloride (common salt) in water. A solution containing
23·5 per cent. of sodium chloride begins to solidify
at -22° C.; the separating solid is not simple sodium chloride
or simple ice, but has the same percentage composition as
the original solution, and thus the temperature remains
-22° until the whole material has become solid. On
microscopic examination the solid is seen to be heterogeneous,
and to consist of small particles of sodium chloride
and ice lying side by side. If the percentage of sodium
chloride is different from 23·5, whether higher or lower,
solidification begins before the temperature has fallen to
-22°. The characters of this particular solution are thus
closely analogous to those of the eutectic mixtures described
above. If the sodium chloride exceeds 23·5 per cent., the
excess of sodium chloride begins to separate, and solidify, at
various parts of the liquid, at a temperature higher than -22°;
it continues to separate, and the temperature to fall, until the
proportion of sodium chloride in the residual liquid is reduced
to 23·5 per cent. and the temperature to -22°. Afterwards
the separating solid has the same composition as the residual
liquid (23·5 per cent. of sodium chloride), and the temperature
remains constant, until the residual liquid has been
wholly transformed into a solid fine-grained mixture of
sodium chloride and ice. The final solid thus consists of
large particles of sodium chloride dispersed through a fine
groundmass consisting of eutectic mixture of sodium chloride
and ice. Similarly, if the water is in excess of 76·5 per
cent., the final solid consists of large particles of ice dispersed
through a fine groundmass consisting of eutectic mixture of
sodium chloride and ice.
The results of the cooling of a solution of ferric chloride
are still more complicated; for this substance enters into
chemical combination with water, and in no fewer than four
different proportions. The solid which first separates from
the cooling solution may thus, according to the percentage
of ferric chloride, be either ferric chloride or water, or any
one of the various compounds of the two; and to each
pair of compounds nearest to each other in composition
corresponds a different eutectic mixture and a different
temperature for its formation.
Cooling of solids.
38. Some solid bodies, during cooling, show changes
analogous to those observed in solutions, and are therefore
termed "solid solutions." For instance, if a hot physically
homogeneous solid obtained from the fusion of iron with
carbon is cooled, there may result a separation in the solid
of particles of either iron or cementite, the latter being a
chemical compound of iron and carbon represented by the
formula Fe3C; the particular substance separated depending
on the percentage composition of the original solid. This
separation continues, and the temperature falls, until the
residual physically homogeneous material contains 0·9 per
cent. of carbon and the temperature is 690°; the temperature
then remains constant, although the body is surrounded by
a cooling medium, until this residual physically homogeneous
material has been wholly transformed into a fine-grained
mixture of iron and cementite, containing 0·9 per cent. of
carbon. This particular kind of mixture has been termed
eutectic, though the transformation has taken place, not by
solidification from fusion, but in a body which was already
solid. Prof. Rinne has proposed for such cases the substitution
of the term eutropic, thus avoiding the suggestion
of fusion. The eutectic mixture of iron (or ferrite) and
cementite is known as pearlite.
Overcooling.
39. Just as water may be cooled so quietly that it is still
liquid at a temperature much below the normal freezing
point, a mixture may be cooled in such a way as to pass
much below the eutectic (or eutropic) point without the
normal transformation taking place; it is then said to be
overcooled. The equilibrium, however, is very unstable, and
the transformation, once begun, takes place almost instantaneously
throughout the whole mass.
Crystalline structure of artificial iron.
40. A structure analogous to that shown by the Widmanstätten
figures, though on a finer scale, has been observed
by Prof. J. O. Arnold and Mr. A. McWilliam17 in cast steel
containing 0·4 per cent. of carbon; the plates of iron (or
ferrite) in the cast steel correspond to the plates of kamacite
in meteorites. Further, it has been found that the plates
in the cast steel disappear during the process of annealing;
similarly, there are no Widmanstätten figures, and the
structure of the material is granular, near the outer surface
of an unweathered meteoric iron; presumably as a result of
the high temperature to which the outer part of the mass
has been raised during the passage of the meteorite through
the earth's atmosphere.
Structure of meteoric irons.
41. At present it is generally imagined that kamacite
and tænite are definite alloys, or perhaps solid solutions, of
iron and nickel, the former being poor in nickel (6 or 7 per
cent.) and the latter rich in that constituent (25 to 38 per
cent.), that kamacite and tænite separate in succession from
the molten mass or solid solution until the residual part is
so rich in nickel that a eutectic (or eutropic) proportion is
reached; the residual material then forms plessite, which,
according to this view, is a eutectic (or eutropic) mixture of
kamacite and tænite. But it is difficult to understand how
the thin plates of tænite are deposited on the plates of
kamacite, seeing that they contain more nickel than kamacite
and plessite, and yet have an intermediate epoch of formation,
prior to the epoch of formation of that tænite which is
a constituent of the plessite; one suggestion is that the thin
plates of tænite have been deposited on the plates of kamacite
owing to the temperature having fallen well below the
eutectic (or eutropic) point after the separation of the
kamacite and before the eutectic transformation of the
residual material has taken place. And Prof. Rinne18 himself
is of opinion that the Widmanstätten structure has been
wholly developed in meteoric iron after the solidification of
the mass; further, as the relations of the kamacite, tænite
and plessite to the enclosed troilite indicate that the troilite
was solid before the octahedral structure was developed, and
as that mineral, under normal circumstances, solidifies
at about 950°, he infers that the structure was developed
below that temperature. In the case of the Jewell (Duel)
Hill meteorite it was discovered by Dr. Brezina that, notwithstanding
the pronounced octahedral structure, plates of
troilite are embedded, not in accidental positions nor between
successive octahedral layers, but parallel to the faces of the
corresponding cube; whence Prof. Rinne suggests that this
iron, now of octahedral structure, and possibly all others of
a similar character, had a cubic structure at the epoch when
they entered upon the solid condition. But, as both Prof.
Rinne and Dr. Brezina19 have pointed out, a fused mixture
of nickel and iron, cooling undisturbedly in outer space,
may have solidified at a temperature even below 950° and
thus have been much overcooled.
Tænite possibly a eutectic mixture.
42. In the course of a recent elaborate investigation of
the changes of the magnetic permeability of the Sacramento
meteoric iron with changing temperature, Mr. S. W. J. Smith20
has been led to infer that the magnetic behaviour can only
be explained by imagining the meteorite to consist largely
of plates of nickel-iron, containing about 7 per cent. of
nickel (kamacite), separated from each other by thin plates
of a nickel-iron constituent (tænite), containing about 27 per
cent. of nickel and having different thermo-magnetic characters
from those of kamacite; he suggests, however, that
tænite is not a definite chemical compound, but is itself a
eutectic (or eutropic) mixture, and consists of kamacite and
a nickel-iron compound containing not less than 37 per
cent. of nickel. And he points out that, while the tænite
mechanically isolated from meteorites for analysis has
approximately the lower percentage (27 per cent.), the
tænite chemically isolated through the prolonged action of
dilute acid (which would remove much of the admixed
kamacite) has a higher percentage, which in several cases
approximates to 40 per cent.
Few siderites have been seen to fall.
43. The Siderites actually observed to fall, or found soon
after a luminous meteor had been seen, or a detonation
heard, by people in the neighbourhood, reach only the small
number of nine; they are, Agram, Charlotte, Braunau,
Victoria West, Nedagolla, Rowton, Mazapil, Cabin Creek,
and N'Goureyma. The remaining specimens in collections
of Siderites are presumed to be of meteoric origin by reason
of the peculiarity of their appearance and chemical composition,
and of the characters of the material in which they
have been found (Art. 7).
Siderites of large size.
The large Cranbourne meteorite, mounted in a special case
in the Pavilion, before rusting weighed 3½ tons. The two
largest known were found in Western Greenland and Mexico,
respectively, and are both of very irregular shape. The
Greenland mass is 11 feet long, 7½ feet wide, and 6 feet
thick, and its weight, which had been variously estimated
at from 50 to 100 tons, has been determined to be 36½ tons;
the mass had long been known to the Eskimos, and was
inquired after by Captain John Ross in 1818; it was shown
by a native to Lieutenant Peary in 1894, who afterwards
transported it from Melville Bay to New York; it is now
preserved in the American Museum of Natural History in
that city. The Mexican mass is 13 feet long, 6 feet wide,
and 5 feet thick, and has an estimated weight of 50 tons;
it is the property of the Mexican Government, and is still
lying at El Ranchito, near Bacubirito, Province of Sinaloa.
The iron found at Ovifak is probably of terrestrial origin.
44. The difficulty of distinguishing an iron of terrestrial
from one of meteoric origin was rendered very evident by
the prolonged controversy as to the origin of the large
masses of iron, containing one or two per cent. of nickel, and
weighing 9,000, 20,000, and 50,000 lbs., respectively, found
in 1870 by Baron N. A. E. Nordenskiöld on the beach at
Ovifak, Disko Island, Western Greenland.
A careful examination of the rocks of the neighbourhood
shows that the basalt contains nickeliferous iron disseminated
through it, and that the large masses of iron,
Pane 4m.
at first thought to be meteorites, are very probably of
terrestrial origin, and have been left exposed upon the seashore
through the weathering of the rock which originally
enclosed them. Some of the malleable metallic nodules
extracted from the basalt were found to contain as much
as 6·5 per cent. of nickel. In 1880 Professor K. J. V.
Steenstrup21 found ferriferous basalt in situ in three different
parts of the island. At Assuk (Asuk) the enclosed balls of
iron reach a diameter of nearly three-quarters of an inch.
Some assert that the basalt and the nickel-iron have been
expelled together from great depths below the earth's
surface, while others consider that the nickel-iron is due
to the reduction of the iron-compounds in the basalt by the
passage of the lava through the beds of lignite and other
vegetable matter found in the vicinity.
Pane 4m.
Other terrestrial irons.
45. With the Ovifak iron in the case are shown other
specimens of iron which have been brought by various explorers
from West Greenland, and were formerly thought
to have had a meteoric origin. The discovery of ferriferous
basalt, not only in situ in several places, but also deposited in a
Greenlander's grave (1879) along with knives (similar to those
given to Captain John Ross in 1818) and the usual stone
tools, renders it clear that the Eskimos were not dependent
solely on meteorites for their metallic iron, as had long been
supposed.
Mr. Skey announced in 1885 the discovery of terrestrial
nickel-iron in New Zealand. Grains of the alloy (Awaruite),
containing as much as 67·6 per cent. of nickel, are found in
the sand of the rivers flowing from a range of mountains
composed of olivine-enstatite rocks, in places altered to
serpentine: similar particles have been found in the serpentine
itself. Similarly, in the sand of the stream Elvo, near
Biella, in Piedmont, and of the river Fraser, British
Columbia, grains of nickel-iron containing 75 or 76 per
cent. of nickel have been found: and in the placer gravel of
a stream in Josephine and Jackson Counties, Oregon, U.S.A.,
large quantities of waterworn pebbles, which enclose an alloy
(Josephinite) of nickel and iron containing 72 per cent. of
the former metal, have been met with. Professor Andrews
many years ago established the presence of minute particles
of metallic iron in some basalts; Dr. Sauer has lately found
a single nodule of malleable iron of the size of a walnut in
the basalt of Ascherhübel, in Saxony; Dr. Hornstein has
described large nodules of (nickel-free) iron found in basalt
in a quarry at Weimar, near Cassel; Dr. Beckenkamp has
described nodules of metallic iron found in clay at Dettelbach,
near Würzburg; and Dr. Johnston-Lavis has announced
the find of an enclosure of metallic iron in a leucitic lava of
Monte Somma; Dr. Hoffmann has noted the occurrence of
minute spherules of brittle iron both in perthite and
quartzite in Ontario; Dr. Hussak has recorded the discovery
of metallic iron in an alluvium of Brazil, and Dr. Högbom
has found it associated with topaz, quartz, felspar, and other
minerals, in limonite from an unspecified place in South
America; two minute grains of iron were found by Mr.
Osaka in the débris of an agglomerate at Nishinotake,
Japan.
The stony matter of meteorites.
46. The stony part of the siderolites and aerolites is
almost entirely crystalline, and in most cases presents a
peculiar "chondritic" or granular structure, the loosely
coherent grains being composed of minerals similar to
those which enclose them, and containing in most cases
minute particles of iron and troilite disseminated through
them: glass-inclusions are found to be present. The minerals
mentioned above as occurring in meteorites are such as are
very characteristic of the more basic terrestrial rocks, such
as dunite, lherzolite and basalt, which have been expelled
from considerable depths below the earth's surface.
47. Several attempts to classify aerolites according to
their mineralogical constitution have been made, but it
cannot be said that any of them is very satisfactory; seeing
that even in the same stone there may be much difference
in its parts, a perfect classification on such a basis is scarcely
to be hoped for.
Chondritic aerolites.
About eleven out of every twelve of the stony meteorites
belong to a division to which Rose22 gave the name of
chondritic (chondros, a grain): they present a very fine-grained
but crystalline matrix or paste, consisting of olivine
and enstatite or bronzite, with more or less nickel-iron,
troilite, chromite, augite and anorthic felspar; through this
paste are disseminated round chondrules of various sizes
(up to that of a walnut) and with the same mineral composition
as the matrix; in some cases the chondrules consist
wholly or in great part of glass.23 In mineral composition
chondritic aerolites approximate more or less to terrestrial
lherzolites. Some meteorites consist almost solely of chondrules,
others contain only few; in some cases the chondrules
are easy separable from the surrounding material. Of the
chondritic division Knyahinya, Pegu, Muddoor, Seres,
Pane 4n.
Judesegeri, Khiragurh, Utrecht and Nellore (pane 4p) afford
good illustrations.
A carbonaceous group.
A few meteorites belonging to this division are remarkable
as containing carbon in combination with hydrogen and
oxygen. Of these the Alais and Cold Bokkeveld meteorites
Pane 4n.
are good examples: the former has a bituminous smell; it
yields sulphates of magnesium, calcium, sodium and potassium,
if steeped in water.
Aerolites without chondrules.
Pane 4o.
48. The remaining aerolites are not chondritic, and they
contain little or no nickel-iron; of these we may specially
mention for their mineral composition the following:—
Juvinas and Stannern, consisting essentially of anorthite
and augite.
Petersburg, consisting of anorthite, augite and olivine,
with a little chromite and nickel-iron: both Juvinas and
Petersburg may be compared to terrestrial basalt.
Sherghotty, consisting chiefly of augite and maskelynite.
Angra dos Reis, consisting almost wholly of augite;
olivine is present in small proportion.
Bustee, of diopside, enstatite and a little anorthic felspar,
with some nickel-iron, oldhamite and osbornite.
Bishopville, of enstatite and anorthic felspar, with occasional
augite, nickel-iron, troilite and chromite.
Roda, of olivine and bronzite.
Chassigny, consisting of olivine with enclosed chromite,
and thus mineralogically similar to a terrestrial dunite.
Is there a periodic recurrence?
49. The importance of the examination and classification
of meteorites, with a view to a possible recognition of
periodicity of fall of specimens presenting the same characters,
need only be mentioned to be appreciated: such a
determination is, however, rendered very difficult by the
close similarity of structure and composition presented by
the great majority of the aerolites of the large chondritic
division.
Few aerolites are known which have not been seen to fall.
50. Attention has been already directed to the fact that
although many masses of meteoric iron, some of them like
that of El Ranchito, near Bacubirito, in Mexico, weighing
very many tons, have been found at various parts of the
earth's surface, very few of them have been actually observed
to fall: in the case of the stony meteorites just the opposite
holds good, for they are never very large, and few are known
which have not an authenticated date of fall. This may be
due to the fact that a meteoric stone is less easily distinguished
than is a meteoric iron from ordinary terrestrial
bodies, and will thus in most cases remain unnoticed unless
its fall has been actually observed; while, further, a quick
decomposition and disintegration must set in on exposure to
atmospheric influences. The smaller size of the meteoric
stones may be due to the greater ease with which they break
up on the sudden increase of temperature of their outer
surface, consequent on their entry into the earth's atmosphere.
The largest meteoric stone preserved in a Museum
is one which fell as part of a shower at Knyahinya,
Hungary, in 1866: it weighs 647 lbs. and is at Vienna. A
larger stone (723 lbs.) fell at Tabory, Russia, in 1887, but
was broken to pieces by the impact on the earth; fragments
of a still larger single stone, weighing at least 1244 lbs.,
were found near together at Long Island, Kansas, U.S.A.,
but the fall was not observed.
The chondrules and their matrix.
51. If we now examine minutely the structure of the
meteoric stones, it will be seen that almost all of them
appear to be made up chiefly of irregular angular fragments,
and that some of them bear a close resemblance to
volcanic tuffs. In the large group of chondritic aerolites,
chondrules or spherules, some of which can only be seen
under the microscope while others reach the size of a
walnut, are embedded in a matrix, apparently made up of
minute splinters such as might result from the fracture of
the chondrules themselves. In fact, until recently, it was
thought by some24 that the chondrules owe their form, not
to crystallisation, but to friction, and that the matrix was
actually produced by the wearing down of the chondrules
through collision with each other either as oscillating components
of a comet or during repeated ejection from a
volcanic vent of some small celestial body. Chondrules
have been observed, however, presenting forms and crystalline
surfaces incompatible with such a mode of formation,
and others have been described which exhibit features
resulting from mutual interference during their growth.
The crystallisation of the chondrules is independent of
their form, and must have started, not at the centre, but at
various places on their surfaces; Dr. Sorby25 argued that
some at least of the chondrules must once have fallen as drops
of fiery rain, and have assumed their shape in an atmosphere
heated to nearly their own temperature. The chondritic
structure is different from anything which has been observed
in terrestrial rocks, and the chondrules are distinct in
character from those observed in perlite and obsidian.
After much study, Dr. Brezina26 lends his weighty support
to the hypothesis that the structural features of meteorites
are the result of a hurried crystallisation: and Prof. Wadsworth27
accepts the same interpretation.
Some meteoric materials appear to have been altered since their consolidation.
Pane 4o.
52. Since the time of their consolidation some meteoric
stones, as Tadjera, appear to have been heated throughout
their mass to a high temperature: and in the case of Orvinio,
Chantonnay, Juvinas, and Weston, fragments are cemented
together with a material having the same composition as
the fragments themselves, thus giving rise to a structure
resembling that of a volcanic breccia. Others seem to have
experienced a chemical change, for some of the chondrules in
Knyahinya and in Mezö-Madaras, when examined with the
microscope, are found to be surrounded by spherical and
concentric aggregations of minute particles of nickel-iron,
perhaps due to the reducing action of hydrogen at a high temperature.
Others, as Château-Renard, Pultusk and Alessandria,
present what in terrestrial rocks would probably be called
faults: in some cases the fissures are seen to have been filled
with a fused material after the chondrules have been broken
and one side of the fissure has glided along the other. These
peculiarities of structure suggest that the small body which
reaches the earth is only a minute fragment of a much
larger mass. It has been suggested that the chondritic
structure is of metamorphic origin, and a mere result of
enormous pressure on the stony material during the passage
through the earth's atmosphere; according to still another
view, the structure, though metamorphic, is of extra-terrestrial
origin, and due to the quick cooling of a tuff-like stone which
has been partially melted, for instance, by the heat from a
neighbouring new star or by traversing the hot vapours on
the limits of an old one.
Do meteorites reach our atmosphere as clouds of gas or dust?
53. The idea that meteorites arrive at our own atmosphere,
not as fragments of rock, but as mere clouds of gas or dust, has
been recently revived and again discarded. According to this
hypothesis, the air, instead of dispersing the entering cloud,
acts in the contrary way, and in a few seconds of time presses
the particles together to form solid bodies. This idea is
open to various objections, and in any case one can scarcely
understand how large masses of iron, presenting a wonderful
regularity of crystalline structure, can have been the result
of so hurried a process: and if we once grant that the irons
enter the atmosphere as solid bodies, it is difficult to believe
that the same is not the case with the stones.
Where do meteorites come from?
54. From the above it will be evident that the old hypotheses
that meteorites are terrestrial stones which have been struck
by lightning, or carried to the sky by a whirlwind, or are
concretions in the atmosphere, or are due to the condensation
of a dust-cloud coming from some volcano, or have been shot
recently from terrestrial volcanoes, are inconsistent with
later observation; it may be granted that the bodies reach
our atmosphere from outer space. From what part or
parts of space do they come? Their general similarity
of structure and chemical composition, and more especially
the presence of nickeliferous iron in almost every one,
suggest that most, if not all of them, have had a common
source, and that they are chips of a single celestial body.
Probably not from the sun, nor from the moon, earth, or other planet.
55. Dr. Sorby suggested that they are probably ejected
from the sun itself, though this is difficult to reconcile with
the fact that some of them are easily combustible. Others,
among whom we may mention Laplace, have suggested that
they come from volcanoes of the moon which are now active;
but the suggestion, although mathematically sound, has no
physical basis, for, so far as one can discover, active volcanoes
do not there exist: and Sir Robert Ball28 has virtually excluded
the lunar volcanoes, which were active in times now
long past, by pointing out that if a projectile from the moon
once misses the earth, its chance of ever reaching the earth
is too small to be worthy of mention. It has further been
shown that, although the explosive force necessary to carry
a projectile so far from one of the smaller planets that it
will not return, is not very large, yet the initial velocity
requisite to carry the body as far as the earth's orbit is so
considerable, and the chance of hitting the earth so slight,
that a more probable hypothesis is, to say the least, desirable.
If these bodies have been shot from volcanoes of any planet,
Sir Robert Ball is himself inclined, upon mechanical grounds
alone, to believe that the projection was from our own in bygone
ages; for as such projectiles, having once got away from
the earth, would take up paths round the sun which would
intersect the earth's orbit, every one of them would have a
chance of some time or other meeting with the earth again
at the point of intersection, and of appearing as a meteorite.
The size and initial velocity requisite for the escape of a
projectile through a lofty atmosphere would be enormous:
even then the difficulty would still remain that meteorites
generally differ, both in structure and material, from anything
known to have been ejected from existing terrestrial
volcanoes. To meet these difficulties, Sir Robert has
speculatively suggested that the matter was expelled before
the surface of the earth became solid, and at a time when
there was as much activity in the terrestrial planet as there
is now in the material of the sun itself.
Nor is it probable that they are portions of a lost satellite
of the earth, or are due to a collision of two planets; for in
each of these cases we should expect to have received some
of the larger fragments which must at the same time have
been produced.
Much light is thrown on the history of meteorites by
the discovery of a relationship with shooting stars and
comets.
Shooting or falling stars.
56. The meteorite-yielding fireball, referred to in Art. 17,
is not the only luminous meteor, apart from lightning, with
which we are acquainted. On a clear dark night any one
can see a star shoot now and then across the firmament: it
is estimated that on the average as many as fourteen are
visible to a single observer every hour. Are the shooting, or,
as they are often called, falling stars products of our own
atmosphere, or do they, like the meteorites, come from outer
space? In 1794 Chladni, in the memoir already referred to,
gave reasons for believing that a meteoritic fireball and a
shooting star are only varieties of one phenomenon.
The November star-showers.
57. But long after the cosmic origin of meteorites had
been generally acknowledged, the atmospheric origin of the
shooting stars was still asserted, and it was not till the
wondrous star-shower of November 12-13, 1833,29 that the
cosmic origin of any of the shooting stars was finally established.
During that night upwards of 200,000 shooting
stars, according to a rough estimate, were seen from a single
place; and the remarkable observation was made at various
localities, widely distributed over North America, that the
apparent paths of the shooting stars in the sky, when
prolonged backwards, all passed through a point in the
constellation Leo: this point of radiation appeared to rotate
with the heavens during the eight hours for which the
shower was visible.
Hence it was manifest that the star-shower was independent
of the earth's rotation and must therefore have come
from outer space; that the radiation of the paths was only
apparent and due to perspective; and that, relatively to an
observer, the flights of all the shooting stars were really
parallel to the direction of the apparent radiant point.
On the same day of November in each of the three following
years the shower was repeated though on a less grand scale,
and the constancy of the radiant point was confirmed:
similar small showers had been seen also in 1831 and 1832
before the radiation had been noticed. Though in the years
immediately before and after 1831-6 no remarkable display
of November meteors took place, it was remembered that a
similar shower had been chronicled by Humboldt and by
Ellicott, as observed by them on November 12, 1799; and a
study of ancient documents revealed the fact that a grand
star-shower had been recorded several times in October and
November since A.D. 902, the date having gradually advanced,
during that long space of time, from the middle of October
to the middle of November.30 The only sufficient explanation
of the observed facts is that a swarm of isolated small
bodies, solid and non-luminous—meteorites in fact—is moving
in an orbit round the sun, completing the circuit in 33¼
years; the orbit intersects that of the earth, and the earth
meets the swarm at the place of intersection. The isolated
bodies or meteorites become luminous, as already explained
in Art. 17, after their entry into the earth's atmosphere.
The swarm can be only a few hundred thousand miles thick,
for the earth, travelling through space at the rate of 66,000
miles an hour, passes through the densest part in 2 or 3
hours, and through the whole in 10 to 15 hours: its length,
however, must be enormous, amounting to hundreds of
millions of miles; for, although the meteorites move with
a velocity of twenty miles a second, the swarm takes 5 or
6 years to pass the place of intersection with the earth's
orbit, thus causing star-showers, more or less dense, during
that number of years.
Contrary to expectation, no large November star-shower
occurred either in the year 1899 or in the years which have
since elapsed.
Schiaparelli has shown that the unequal attraction of the
sun for the individuals of a swarm of meteorites moving
round it would scatter them along the orbit, and in the
course of time produce a more or less complete ring; if this
intersects the earth's orbit an annual star-shower must ensue.
The August star-shower and its comet.
58. A small annual star-shower occurs, in fact, on August
10-11,31 and has been observed since A.D. 830: it radiates
from a point in the constellation Perseus. Schiaparelli
calculated in 1866 the orbit and motion of the meteorites producing
it, and was surprised to find that the numbers corresponded
exactly with those calculated for one of the recently
observed comets; in other words, a comet was moving in
the path of the meteorites, and at exactly the same speed.
At the same time Schiaparelli gave numbers defining the
motions of the meteorites which would cause the periodic
November star-showers.
Star-showers related to comets.
59. Immediately afterwards, when the numbers calculated
by Oppolzer for the orbit of the comet discovered by
Tempel were published, it was seen that they were really
identical with those already calculated by Schiaparelli for
the orbit of the meteorites of the November star-shower,
and that here again a comet and a swarm of meteorites were
moving in exactly the same path at exactly the same rate.
Almost immediately afterwards it was shown that the
radiant points of the small star-showers of April 20-21
and November 27-28 both correspond to the orbits of
known comets.
It was evident that these could not be accidental
coincidences, and that the comets and the attendant swarms
of meteorites are closely related to each other.
Comets.
60. An intimate connection between, if not complete
identity of, meteorites, shooting stars and comets, had indeed
long been suspected. Astronomers were convinced
that comets, though occasionally of enormous size, are always
of extremely small mass, since they pass by the earth and
other planets without sensibly disturbing their motions;
the comet of 1770 passed through the system of Jupiter's
satellites without any perceptible action upon them: it
has been calculated that the mass of a small comet may be
about eight pounds. Again, the light of a comet, like that
of a cloud or planet, was seen to be partially polarised: hence
part, at least, must be reflected sunlight, for the plane of
polarisation passes through the sun's place. Further, stars
of very small magnitude have been seen not only through
the tail, but even through the nucleus, of a comet without
any apparent alteration of position by refraction: hence it
was inferred that a comet is not a continuous mass, but
consists of particles so far distant from each other that a
ray of light may pass through the comet without meeting
a single one of them. Such a constitution likewise accounts
for the absence of phases of the reflected light: for although
only half of each particle will be directly illuminated by the
sun, the remaining half will receive light irregularly reflected
from the particles more distant from the sun.
Among others, Chladni in 1817 had referred to the great
similarity in the motions of comets and meteorites: Olmsted,
in 1834, had calculated the orbit of a comet which would
cause the November star-shower; his results were wrong
owing to the assumption that the shower was annual:
Cappocci, in 1842, gave reasons for believing that a meteorite
is a small comet: Reichenbach, in 1858, in a most elaborate
paper,32 sought to prove that a comet is a swarm of
meteorites; that each chondrule of a meteorite had once
been an individual of a cometary swarm, and owes its rounded
shape to frequent collision with its fellows; that the rest
of the stone consists of the broken splinters thus produced;
and that the brecciated aspect of many meteorites is due to
collisions in the denser part or nucleus of a comet. As
already pointed out in Art. 51, later modes of investigation
have led petrologists to reject this method of accounting for
the rotundity of the chondrules.
Other star-showers.
61. In addition to the few radiant points which correspond
to swarms moving in orbits identical with those of known
comets, there are numerous radiant points which have not
yet been recognised as related to existing comets, and may
possibly be due to swarms produced by the dispersal of
comets along their orbits; indeed, it has been inferred from
observation of shooting stars that on the average there are
no fewer than fifty distinct radiant points, and therefore
showers, for any night of the year. But there are still
others of which there is yet no satisfactory explanation. A
cometary swarm is thin, and is passed through in a few hours;
the stars are seen to radiate from the corresponding point
of the sky for only that length of time: but there are other
radiant points which have a duration of several months, and
this is the case notwithstanding the constantly changing
direction of the earth's motion in space.33 Since the position
of the radiant point in the sky as seen by a terrestrial observer
depends not only on the direction in which the swarm
is moving, but also on the velocity and direction of motion of
the observer through space, it is easily seen that a radiant
point having a fixed position during some months corresponds
to something quite distinct from a cometary swarm. It has
been suggested by Mr. W. F. Denning (1899) that in some
cases a long-continued radiant point may really be due, not
to a single swarm, but to successive swarms not physically
associated with each other. On the other hand, Professor
H. H. Turner has shown that the average effect of the earth's
attraction on a meteorite passing near it is to change only
the position in our orbit at which we meet the meteorite
(i.e. the time of year), not the relative-direction of motion
or the relative speed; hence, a swarm of such meteorites
must be spread out, in the course of ages, into a succession
of rings, all of them equally inclined to the earth's orbit,
but intersecting it at different places; the radiant point
will then be of long duration. Professor A. S. Herschel34
made the suggestion that the radiant points of long duration
may have resulted from the passage, in bygone epochs,
of quickly moving streams of cosmical matter through
a ring of small bodies circulating, as satellites, round the
earth.
Daily and yearly maxima of shooting stars.
62. The rotation of the earth round its axis is such that
the part furthest from the sun, for which it is therefore
midnight, is moving in the same direction as the earth in
its orbit; whence, at the part of the earth most forward in
the orbit it is sunrise, and at the part most backward it is
sunset. Thus, as Schiaparelli pointed out, the meteorites
which enter the atmosphere in the first half of the night are
more or less following the earth in its orbit, and have their
velocity relative to the earth diminished by the earth's own
motion of translation; they are thus less likely to produce
shooting stars than those which enter the atmosphere in the
second half of the night and are travelling more or less oppositely
to the earth as it moves in its orbit, and have their
relative velocity increased. Hence, if the directions of flight
of meteorites were uniformly distributed in space, the number
of shooting stars hourly visible at one place, a number which
would be constant if the earth were at rest, would gradually
vary during the night, reaching a maximum about 3 A.M.
Also, as the point in space towards which the earth is
moving in its orbit varies in height above the horizon during
the year, being highest in autumn and lowest in spring, the
number of shooting stars hourly visible at one place will
gradually vary from night to night, reaching a maximum in
the former season and a minimum in the latter, if the directions
of flight of the meteorites be themselves uniformly
distributed in space.
The breaking up of comets.
63. The history of Biela's comet35 is of great interest as
throwing light on the relationship of comets and swarms of
meteorites. Though already observed in 1772 and in 1806,
this comet was not recognised as periodic till it was seen
by Biela in 1826, when its orbit was determined. On its
returns in 1832 and 1845 it was found in its calculated
positions, but in the latter year was seen to be double, a
small comet being visible beside a larger one. Vast changes
took place during the time the companions were visible.
The smaller one grew both in size and brightness, each
threw out a tail, the smaller threw out a second tail, afterwards
the larger showed two nuclei and two tails, then the
smaller became the brighter of the two companions; next
three tails were shown by the primary, and three cometary
fragments were visible round its nucleus. On the next
return, in 1852, the two comets were farther apart, one
being more than a million miles ahead of the other. The
next favourable return was to be in 1866, and the orbit was
by this time so well known that the positions of the two companions
could be calculated beforehand with great precision;
owing to the changes which had been visibly taking place,
the arrival of the comets was looked forward to with great
interest by astronomers. But neither in 1866, nor on the
next occasion in 1872, were they to be seen in their calculated
positions, and a careful examination of the whole sky failed
to lead to their discovery.
The connexion between several comets and meteoritic
swarms having in the meantime been established, it was now
surmised that Biela's comet might have been scattered along
part of its path, and that some evidence of the dispersal
might perhaps be obtained on the next occasion, November
27, 1872, of the passage of the earth across the comet's
orbit. In fact the star-shower of that date, with a radiant
point corresponding to the orbit of Biela's comet, was observed
to be much more dense than usual, the stars shooting across
the sky at the rate of a thousand an hour for several hours.
Passage of the earth through a comet.
64. Klinkerfues, a German astronomer, was struck with
the idea that if this star-shower were really due to the
passage of the earth through a moving swarm of meteorites,
the latter might possibly be visible as it departed from our
neighbourhood. The swarm having come from a radiant
point in the northern sky, after passing the earth would
need to be sought near the opposite point in the southern
sky; he telegraphed, therefore, to the Madras observatory,
asking Pogson, the astronomer, to search for the swarm in
the direction opposite to the radiant point. The search was
successful; on two mornings a small comet was distinctly
seen, and on the second morning it showed a tail with an
apparent length equal to one-fourth the apparent diameter of
the moon. Bad weather came on, and the comet got away
without being again seen. The two Madras observations
agree with a motion in the orbit of Biela's comet, and show
that the earth had passed excentrically through the small
comet seen by Pogson. This small comet was probably a
third fragment of Biela's, for it was 200 million miles
behind the calculated position of the first two. From these
two observations it is inferred that a swarm of meteorites,
though only manifesting itself by a star-shower when passing
through the earth's atmosphere, at some distance from us
may be visible as a comet by reflected sunlight.
Fall of a meteorite during a star-shower.
65. A dense star-shower36 recurred on the same day of
the month (November 27) in 1885, the principal part being
over in six hours. The hourly number visible at one place
at the time of greatest density was estimated at 75,000. In
the densest part of the stream, the average distance of the
individuals from each other was about twenty miles.
During this star-shower a piece of iron weighing about 8 lbs.
was seen to fall at Mazapil in Mexico:37 in external characters
and chemical composition it is similar to the other meteoric
irons: the simultaneity was probably accidental.
The reason of its rarity.
66. It may be asked why, if star-showers are caused by
the entry of solid bodies into our atmosphere from without,
there is only one authentic instance of material being actually
seen to fall and being picked up during such a shower. As
it is absolutely beyond question that star-showers do come
from outer space, we can seek an explanation only in the
size or speed of the entering individuals, or in the nature of
their material. A sufficient reason is to be found in the
small size of the individuals; for the meteorites which
actually reach the ground rarely weigh more than a few
pounds, and are often quite minute; a small diminution of
the original individual would thus ensure its complete destruction
before the planetary velocity was exhausted: that
the individuals of a swarm are extremely minute follows from
the fact that the total mass of the biggest swarm is small,
while the number of the individuals seems almost infinite.
Large and small luminous meteors essentially similar.
67. Between the small silent shooting star visible only
with the telescope and the large detonating meteorite-yielding
fireball there is every gradation; during the star-showers
themselves many fireballs of great size and brilliancy
are seen, while the smaller individuals appear in no way
different from the solitary shooting star. The luminous
meteors, large and small, are in the upper atmosphere, few
higher than 100 miles, few lower than 30 miles from the
earth's surface; they all have velocities of the same order of
magnitude, comparable with that of the earth in its orbit; in
each there must be a solid body, as is proved by the long
path in the sky, for attendant gas or vapour would be immediately
scattered or burnt; large and small present similar
varieties of colour, and leave similar luminous trails; examination
with the spectroscope teaches us that the light of the
meteors is such as would result from the ignition of such
meteorites as have actually reached the ground. The frequent
absence of detonation may likewise be due in many
cases to the small size, or small relative velocity, of the
entering meteorite.
The light of a comet.
68. That part of the light of a comet is reflected sunlight
is confirmed by examination with the spectroscope, in which
instrument is seen a feeble continuous spectrum crossed by
dark lines, identical with those afforded by the direct light
of the sun. But a comet is also more or less self-luminous;
for, in addition to the continuous spectrum, there are bright
flutings and bright lines to which much attention has been
given. The three ordinary bright flutings were found by
Sir William Huggins in 1868 to be identical with the
spectrum obtained when an electric spark is passed through
olefiant gas, and they are now recognised as due to carbon.
The carbon is presumed to be combined with hydrogen,
sometimes also with nitrogen; in the case of comets
approaching very near the sun, the lines of sodium, and
others which have been supposed to be iron-lines, are seen.38
Tait's suggestion.
69. The discovery made by Schiaparelli proves, as already
pointed out, that there is a relationship between comets and
meteoritic swarms; Schiaparelli himself held the view that
a comet and its attendant swarms are merely of identical
origin. In 186939 Tait discussed, from a purely dynamical
point of view, the question as to whether the swarm of
meteorites attending a comet may not really be part of the
comet itself; he showed that many cometary characters
can be mechanically explained on the assumption that
comets are really swarms of small meteorites, and pointed out
that the self-luminosity may be produced by the heating of
the individuals through collision with each other.
Reproduction of the spectrum of a comet.
70. Flutings exactly identical with those seen in the
spectrum of a comet were obtained by Professor A. W.
Wright in 187540 on allowing the electric glow to pass
through a heated tube, in which, after the introduction of
fragments of the Iowa meteorite, the gaseous density had
been reduced by an air-pump. The bright lines, too, in
the spectrum of a comet, even when nearest to the sun,
are found by Sir Norman Lockyer to be identical with
those yielded when the electric glow is passed over ordinary
meteorites at comparatively low temperatures; and further,
the changes in these lines as the comet approaches and
recedes from the sun are exactly those which take place on
variation of the temperature of the meteorites enclosed in
the glow-tubes.
A comet is perhaps a swarm of meteorites.
71. From these facts it is inferred that a comet may be in
every instance a swarm of isolated large or minute meteorites,
at a not very high temperature, shining partly by reflected
sunlight and partly by the electric glowing of the gases
evolved owing to the action of the sun's heat on the meteorites:
further, some of the heat may be due to the clashing
together of the meteorites, the grouping of which becomes
more and more condensed as the swarm approaches the sun.
The gases driven from the meteorites by the sun's heat
would be quite sufficient in quantity to form the tail of
the comet: as pointed out by Professor Wright, a meteorite
like that which fell at Cold Bokkeveld would furnish 30
cubic miles of gas measured at the pressure of our own
atmosphere, and in space itself this gas would expand to
enormous dimensions owing to the small mass and attraction
of the meteoritic swarm. We are still uncertain, however,
as regards the actual physical condition of the matter composing
the tail of a comet.
Saturn's rings are probably swarms of meteorites.
72. Clerk-Maxwell proved, as long ago as 1857, that the
stability of the rings which revolve round the planet Saturn
is inconsistent with their being formed of continuous solid
or liquid matter; and has shown, by mechanical reasoning,
that they must be revolving clouds of small separate
bodies, like cannon-shot, each moving as a satellite and
almost independent of the rest in its motion: determination
of the motions of the inner and outer parts of the ring-system
made with the help of the spectroscope supports this
conclusion.
Nebulæ.
73. Reichenbach, in 1858, before the self-luminosity had
been proved by means of the spectroscope, had imagined a
nebula to be a cloud of isolated meteorites, illuminated by
some neighbouring sun: Chladni, long before, had supposed
a nebula to be a cloud of phosphorescent dust. But, in
1864, it was established by Sir William Huggins that the
light is due, not to reflection or phosphorescence, but to
incandescence, for the spectrum consists of bright lines such
as are yielded by glowing gas. Tait,41 in 1871, suggested that
the nebulæ may be clouds of mutually impinging meteorites,
mingled with glowing gases developed by the impacts;
he pointed out that the heat produced by the clashing of the
individuals of such an immense group as a nebula evidently
is would be quite adequate for the production of their
light. Sir Norman Lockyer finds that the bright lines
(generally accompanied by a certain amount of continuous
spectrum) which have been observed in nebular spectra
are consistent with this suggestion, and regards them as
closely related to the low temperature lines obtained when
a gentle electric glow is passed over meteorite-fragments in
a tube containing gases given out by them, and of which
the density has been reduced by the air-pump; further, he
points out that the nebular spectrum is identical with that
of the comets of 1866 and 1867 when distant from the sun.
According to this suggestion, a nebula and a comet are of
identical constitution, and a comet is merely a nebula which
has become entangled in the solar system. On the other
hand, Sir William Huggins has expressed (1891) the opinion
that the spectrum of the bright-line nebulæ is certainly not
such as we should expect to result from the collision of
meteorites like those which have reached the earth, and that
it is suggestive of a high temperature; he points out that
the particles which have just been in collision may be at
high temperatures and yet the average temperature of all
the particles may be low.
Stars.
74. The examination and classification of the spectra
of the stars has likewise led to remarkable conclusions.
Secchi, following Rutherfurd, found that the stars could be
distributed into classes according to the characters of their
spectra,42 and his classification has since, with little modification,
been adopted by Vogel and Dunér, by whom several
thousand star-spectra have now been systematically mapped.
The first three classes are characterised by absorption, the
fourth by radiation.
In the spectra of Class I the absorption is small and
simple, the dark lines being broad and few; the stars
themselves are white: in one division of this class,
represented by Sirius and Vega, the principal lines are due
to hydrogen; in another important division, represented by
β, γ, δ, ε, ζ Orionis, lines of helium are very pronounced.
In Class II the dark lines are thinner and more numerous;
the stars are bluish-white to reddish-yellow: to this class
belong the Sun, Arcturus, Capella.
The absorption in Class III manifests itself predominantly
as flutings, though there are also many thin lines: the stars
are orange or red: in one division (a) of this class the
darkest part and the sharpest edge of each fluting is
towards the violet end of the spectrum, as in Betelgeux; in
a smaller division (b) the darkest part of each fluting is
towards the red end, as in star 152 Schjellerup; the fluting
absorption of the latter division being due to carbon.
The remaining Class IV is an extremely small one: the
spectra are characterised by bright lines: some of the lines
are due to hydrogen, and others to substances not yet
recognised in terrestrial chemistry.
Supposed cooling of all the stars.
75. Soon after the classification suggested by Secchi had
been announced, it was surmised that the differences in the
stars of the first three classes might be due, not so much to
differences of matter, as to differences of temperature, and
that a very hot star such as, from its brightness and
distance, its small and simple absorption, and the development
of the blue end of its spectrum, Vega is believed to be,
would, on getting older and colder, pass from Class I to
Class II, and thence to one or other of the divisions of
Class III.
New stars.
76. In 1866 a star of 9th or 10th magnitude burst into
greater brilliancy and nearly reached the intensity of
Vega; the spectrum showed the presence of brilliantly
glowing hydrogen. Almost as suddenly the light went
down again, and within a month returned to its original
brightness. Ten years later, another new star of the 3rd or
4th magnitude appeared at a place in the sky where no
star had been noticed before; its spectrum showed numerous
bright lines; gradually, in the course of a year, it dwindled
down to the 10th magnitude, then giving the telescopic
appearance and the spectrum of a nebula. Several other
new stars have since been observed, the most notable being
Nova Persei, which appeared in 1901. In each case, as the
star faded, its spectrum changed into that which is
characteristic of the nebulæ.
The appearance of a new star has been generally attributed
to the collision of two bodies in space; Sir Norman
Lockyer43 has pointed out that the rapidity of the change in
the brilliancy, so different from that of other stars, may be
due to the smallness of the mass, and that such a star may be
produced by the collision of two swarms of widely separated
meteorites. He has shown that the changes in the spectrum
as such a star varies in brightness are confirmatory of
this view.
The heat of the sun.
77. That the heat of our own sun was originated by the
falling together of smaller bodies was, until lately, generally
acknowledged;44 for the only other conceivable natural cause,
known to exist from independent evidence, namely, chemical
combination, was quite insufficient; the greatest amount of
heat obtainable from the most advantageous chemical combination
of any of the then known elements, having a total
mass equal to that of the sun, would not cover the sun's
expenditure for more than three thousand years, while there
is no difficulty on the meteoritic explanation in providing a
supply of heat sufficient to cover the loss by radiation during
20,000,000 years. But the discovery that compounds of
radium maintain themselves at a higher temperature than
that of surrounding bodies and are only inappreciably
changed though continuously emitting an appreciable amount
of heat, shows that the meteoritic hypothesis as to the cause
of the sun's high temperature is not necessarily the true one:
there may be an analogous heat-yielding material in the sun.
In any case the present loss of the sun's heat by radiation
is probably not covered by the fall of bodies into the sun;
for the requisite mass would, if from distant regions,
visibly affect the motions of the planets by its attraction,
and, even if circulating round the sun at no great distance
from it, would seriously disturb the motions of some of the
comets. Further, much heat will result from the shrinkage
of the volume of the solar aggregate.
Evolution of the heavenly bodies.
78. By study of the spectra, at various temperatures, of
the elements and compounds found in those meteorites which
have reached our earth and been preserved, Sir Norman
Lockyer45 has been led to support the view that the stars
are not at present all cooling down, but that some, on the
contrary, are rising in temperature; he suggests that many
of the stars, like the nebulæ, are constituted of separate
meteorites in continual relative motion, and become hotter
and hotter through contraction of the grouping, collision,
and transformation of the energy of position and motion into
heat. This increase of temperature must continue during
successive ages, until the energy of position and motion of
the separate meteorites is wholly transformed, the separate
masses having then combined to form a single white hot
body which will gradually cool down to the state in which
our own moon now is. If a swarm of meteorites forming one
nebula be subjected to the external action of another moving
swarm of meteorites, intermediate stages resembling the
conditions of Saturn and of the solar system may ensue.
According to this spectroscopic affirmation of the nebular
theory, all the heavenly bodies are constituted of the same
kinds of elementary matter, those in fact which are found
in meteorites and our own earth, and the difference is solely
due to temperature; and a nebula in its gradual passage to the
lunar condition will show every phase of spectrum observed
in the stars as now existent.
Meteorites present no evidence of life.
79. Finally, it may be asked whether or not meteorites
bring us any tangible evidence of the existence of living
beings outside our own world. To this we may briefly
answer, that while an organic origin can scarcely be claimed
for the graphite present in the meteoric irons, there are no
less than six meteoric stones which contain, though in very
minute quantity, carbon compounds of such a character
that their presence in a terrestrial body would be regarded
as doubtlessly an indirect result of animal or vegetable
existence. On the other hand, the stony matter is such that
in a terrestrial body an igneous origin would be assumed.
Professor Maskelyne has pointed out that these carbon
compounds can be completely removed without a preliminary
pulverisation of the stone, and thus seem to be contained
merely in the pores; he suggested that they may have been
absorbed by the stones in their passage through an atmosphere
containing the compounds in a state of vapour. In
any case, it is impossible to prove that there is a necessary
relation between these compounds of carbon and the existence
of living beings.
Chondrules have been mistaken for organisms.
80. In 188046 descriptions were given of sponges, corals,
crinoids and plants, found in several meteorites, chiefly in
that of Knyahinya, but the memoir has been generally
regarded as an elaborate jest. The chondrules with their
excentrically radiating crystallisation are there classified and
named as sponges, corals and crinoids, while the structure
of meteoric iron, revealed by the Widmanstätten figures, is
regarded as a result of plant life. There can be no hesitation
in asserting that as yet no organised matter has been found
in meteorites.
Footnotes
- 1.
- Remarks concerning stones said to have fallen from the clouds both
in these days and in ancient times: by Edward King. London, 1796.
Mémoire historique et physique sur les chutes des pierres: par P. M. S.
Bigot de Morogues. Orléans, 1812.
- 2.
- Sitzungsber. d. k. Ak. d. Wiss. Wien. 1856, vol. 22, p. 393.
- 3.
- Records of the Geological Survey of India. Calcutta, 1885, vol. 18, p. 237.
- 4.
- Ueber den Ursprung der von Pallas gefundenen und anderer ihr
ähnlicher Eisenmassen. Riga, 1794.
- 5.
- Reise durch verschiedene Provinzen des russischen Reichs: von
P. S. Pallas. St. Petersburg, 1776, Part III., p. 411.
- 6.
- Philosophical Transactions. London, 1788, vol. 78, part 1, pp. 37, 183.
- 7.
- Philosophical Transactions. London, 1795, vol. 85, p. 103.
- 8.
- Ibid., 1802, vol. 92, p. 174.
- 9.
- Bulletin des Sciences par la Société Philomathique. Paris, 1803,
vol. 3, no. 71, p. 180.
- 10.
- Mémoires de l'Institut National de France. 1806, vol. 7, part 1,
Histoire, p. 224.
- 11.
- Principes de Thermodynamique: par Paul de Saint-Robert. Paris,
1870, p. 329.
- 12.
- The Fall of Butsura: by Prof. Maskelyne. Phil. Mag. 1863, vol. 25, p. 50.
- 13.
- Die chemische Natur der Meteoriten: von C. Rammelsberg. Berlin,
1870-9. Météorites: par S. Meunier. Paris, 1884. Meteoritenkunde:
von E. Cohen. Stuttgart, 1894-1905.
- 14.
- Some lecture-notes on meteorites: by Prof. Maskelyne. Nature, 1875,
vol. 12, pp. 485, 504, 520.
- 15.
- Études synthétiques de géologie expérimentale. Paris, 1879. p. 517.
- 16.
- Phil. Mag. 1884, ser. 5, vol. 17, p. 462.
- 17.
- Nature, 1904, vol. 71, p. 32.
- 18.
- Neues Jahrbuch für Mineralogie, 1905, Band I, p. 122.
- 19.
- Denksch. d. math-naturw. Klasse d. k. Ak. d. Wiss., 1905, Band 78, p. 635.
- 20.
- Philosophical Transactions, London, 1908, Ser. A, vol. 208, p. 21.
- 21.
- Mineralogical Magazine. London, 1884, vol. 6, p. 1.
- 22.
- Beschreibung und Eintheilung der Meteoriten. Berlin, 1864.
- 23.
- Die mikroskopische Beschaffenheit der Meteoriten: von G. Tschermak. Stuttgart, 1883-5.
- 24.
- Pogg. Ann. 1858, vol. 105, p. 438: Phil. Mag. 1876, ser. 5, vol. 1, p. 497.
- 25.
- On the structure and origin of meteorites. Nature, 1877, vol. 15, p. 495.
- 26.
- Die Meteoritensammlung d.k.k. min. Hofkabinetes in Wien. 1885, p. 19.
- 27.
- Lithological Studies. Cambridge, U.S.A. 1884, p. 110.
- 28.
- Speculations on the source of Meteorites. Nature, 1879, vol. 19, p. 493.
- 29.
- Olmsted. American Jour. Sc., 1834, ser. 1, vol. 25, p. 363.
- 30.
- Newton. American Jour. Sc., 1864, ser. 2, vol. 37, p. 377; vol. 38, p. 53.
- 31.
- Report Brit. Assoc., 1868, p. 394.
- 32.
- Pogg. Ann., 1858, vol. 105, p. 438.
- 33.
- Denning. Nature, 1885, vol. 31, p. 463.
- 34.
- Monthly Notices of the Roy. Astron. Soc. 1899, vol. 59, p. 179.
- 35.
- Newton. Nature, 1886, vol. 33, pp. 392, 418.
- 36.
- Newton. American Jour. Sc., 1886, ser. 3, vol. 31, p. 409.
- 37.
- Hidden. American Jour. Sc., 1887, ser. 3, vol. 33, p. 223.
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