The opening of the Eclipse Expedition was not propitious.
Portsmouth, on the 5th of December 1870,
was swathed by a fog, which was intensified by smoke,
and traversed by a drizzle of fine rain. At six P.M. I
was on board the ‘Urgent.’ On Tuesday morning the
weather was too thick to permit of the ship’s being
swung and her compasses calibrated. The Admiral
of the port, a man of very noble presence, came on
board. Under his stimulus the energy which the
weather had damped appeared to become more active,
and soon after his departure we steamed down
to Spithead. Here the fog had so far lightened as
to enable the officers to swing the ship.
At three P.M. on Tuesday the 6th of December
we got away, gliding successively past Whitecliff
Bay, Bembridge, Sandown, Shanklin, Ventnor, and
St. Catherine’s Lighthouse. On Wednesday morning
we sighted the Isle of Ushant, on the French side of
the Channel. The northern end of the island has
been fretted by the waves into detached tower-like
masses of rock of very remarkable appearance. In
the Channel the sea was green, and opposite Ushant
it was a brighter green. On Wednesday evening we
committed ourselves to the Bay of Biscay. The roll
of the Atlantic was full, but not violent. There had
been scarcely a gleam of sunshine throughout the
day, but the cloud-forms were fine, and their apparent
solidity impressive. On Thursday morning I rose
refreshed, and found the green of the sea displaced
by a deep indigo blue. The whole of Thursday we
steamed across the bay. We had little blue sky, but
the clouds were again grand and varied—cirrus,
stratus, cumulus, and nimbus, we had them all.
Dusky hairlike trails were sometimes dropped from
the distant clouds to the sea. These were falling
showers, and they sometimes occupied the whole
horizon, while we steamed across the rainless circle
which was thus surrounded. Sometimes we plunged
into the rain, and once or twice, by slightly changing
course, avoided a heavy shower. From time to time
perfect rainbows spanned the heavens from side to side.
At times a bow would appear in fragments, showing
the keystone of the arch midway in air, and its two
buttresses on the horizon. In all cases the light of the
bow could be quenched by a Nicol’s prism, with its
long diagonal tangent to the arc. Sometimes gleaming
patches of the firmament were seen amid the
clouds. When viewed in the proper direction, the
gleam could be quenched by a Nicol prism, a dark
aperture being thus opened into stellar space.
At sunset on Thursday the denser clouds were
fiercely fringed, while through the lighter ones
seemed to issue the glow of a conflagration. On
Friday morning we sighted Cape Finisterre, the
extreme end of the arc which sweeps from Ushant
round the Bay of Biscay. Calm spaces of blue, in
which floated quietly scraps of cumuli, were behind
us, but in front of us was a horizon of portentous
darkness. It continued thus threatening throughout
the day. Towards evening the wind strengthened to
a gale, and at dinner it was difficult to preserve the
plates and dishes from destruction. Our thinned
company hinted that the rolling had other consequences.
It was very wild when we went to bed.
I slumbered and slept, but after some time was
rendered actively conscious that my body had become
a kind of projectile, which had the ship’s side for a
target. I gripped the edge of my berth to save myself
from being thrown out. Outside, I could hear
somebody say that he had been thrown from his
berth, and sent spinning to the other side of the
saloon. The screw laboured violently amid the
lurching; it incessantly quitted the water, and,
twirling in the air, rattled against its bearings, and
caused the ship to shudder from stem to stern. At
times the waves struck us, not with the soft impact
which might be expected from a liquid, but with the
sudden solid shock of battering-rams. ‘No man
knows the force of water,’ said one of the officers,
‘until he has experienced a storm at sea.’ These
blows followed each other at quicker intervals, the
screw rattling after each of them, until, finally, the
delivery of a heavier stroke than ordinary seemed
to reduce the saloon to chaos. Furniture crashed,
glasses rang, and alarmed enquiries immediately followed.
Amid the noises I heard one note of forced
laughter; it sounded very ghastly. Men tramped
through the saloon, and busy voices were heard aft,
as if something there had gone wrong.
I rose, and not without difficulty got into my
clothes. In the after-cabin, under the superintendence
of the able and energetic navigating lieutenant,
Mr. Brown, a group of blue-jackets were working at
the tiller-ropes. These had become loose, and the
helm refused to answer the wheel. High moral
lessons might be gained on shipboard by observing
what steadfast adherence to an object can accomplish,
and what large effects are heaped up by the addition
of infinitesimals. The tiller-rope, as the blue-jackets
strained in concert, seemed hardly to move; still it
did move a little, until finally, by timing the pull to
the lurching of the ship, the mastery of the rudder
was obtained. I had previously gone on deck.
Round the saloon-door were a few members of the
eclipse party, who seemed in no mood for scientific
observation. Nor did I; but I wished to see the
storm. I climbed the steps to the poop, exchanged
a word with Captain Toynbee, the only member of
the party to be seen on the poop, and by his direction
made towards a cleat not far from the wheel.[44]
Round it I coiled my arms. With the exception of
the men at the wheel, who stood as silent as corpses,
I was alone.
I had seen grandeur elsewhere, but this was a new
form of grandeur to me. The ‘Urgent’ is long and
narrow, and during our expedition she lacked the
steadying influence of sufficient ballast. She was for
a time practically rudderless, and lay in the trough
of the sea. I could see the long ridges, with some
hundreds of feet between their crests, rolling upon
the ship perfectly parallel to her sides. As they
approached they so grew upon the eye as to render
the expression ‘mountains high’ intelligible. At
all events, there was no mistaking their mechanical
might, as they took the ship upon their shoulders,
and swung her like a pendulum. The poop sloped
sometimes at an angle which I estimated at over
forty-five degrees; wanting my previous Alpine
practice, I should have felt less confidence in my
grip of the cleat. Here and there the long rollers
were tossed by interference into heaps of greater
height. The wind caught their crests, and scattered
them over the sea, the whole surface of which was
seething white. The aspect of the clouds was a fit
accompaniment to the fury of the ocean. The moon
was almost full—at times concealed, at times
revealed, as the scud flew wildly over it. These
things appealed to the eye, while the ear was filled
by the whistle and boom of the storm and the
groaning of the screw.
Nor was the outward agitation the only object of
interest to me. I was at once subject and object
to myself, and watched with intense interest the
workings of my own mind. The ‘Urgent’ is an
elderly ship. She had been built, I was told, by a
contracting firm for some foreign Government, and
had been diverted from her first purpose when converted
into a troop-ship. She had been for some
time out of work, and I had heard that one of her
boilers, at least, needed repair. Our scanty but
excellent crew, moreover, did not belong to the
‘Urgent,’ but had been gathered from other ships.
Our three lieutenants were also volunteers. All this
passed swiftly through my mind as the ship shook
under the blows of the waves, and I thought that
probably no one on board could say how much of this
thumping and straining the ‘Urgent’ would be able
to bear. This uncertainty caused me to look
steadily at the worst, and I tried to strengthen
myself in the face of it.
But at length the helm laid hold of the water,
and the ship was got gradually round to face the
waves. The rolling diminished, a certain amount
of pitching taking its place. Our speed had fallen
from eleven knots to two. I went again to bed.
After a space of calm, when we seemed crossing the
vortex of a storm, heavy tossing recommenced. I
was afraid to allow myself to fall asleep, as my berth
was high, and to be pitched out of it might be
attended with bruises, if not with fractures. From
Friday at noon to Saturday at noon we accomplished
sixty-six miles, or an average of less than
three miles an hour. I overheard the sailors talking
about this storm. The ‘Urgent,’ according to those
that knew her, had never previously experienced
anything like it.[45]
All through Saturday the wind, though somewhat
sobered, blew dead against us. The atmospheric
effects were exceedingly fine. The cumuli resembled
mountains in shape, and their peaked summits shone
as white as Alpine snows. At one place this resemblance
was greatly strengthened by a vast area of
cloud, uniformly illuminated, and lying like a névé
below the peaks. From it fell a kind of cloud-river,
strikingly like a glacier. The horizon at sunset
was remarkable—spaces of brilliant green between
clouds of fiery red. Rainbows had been frequent
throughout the day, and at night a perfectly continuous
lunar bow spanned the heavens from side
to side. Its colours were feeble; but, contrasted
with the black ground against which it rested, its
luminousness was extraordinary.
Sunday morning found us opposite to Lisbon, and
at midnight we rounded Cape St. Vincent, where
the lurching seemed disposed to recommence.
Through the kindness of Lieutenant Walton, a cot
had been slung for me. It hung between a tiller-wheel
and a flue, and at one A.M. I was roused by
the banging of the cot against its boundaries.
But the wind was now behind us, and we went along
at a speed of eleven knots. We felt certain of reaching
Cadiz by three. But a new lighthouse came
in sight, which some affirmed to be Cadiz lighthouse,
while the surrounding houses were declared to be
Cadiz itself. Out of deference to these statements,
the navigating lieutenant changed his course, and
steered for the place. A pilot came on board, and he
informed us that we were before the mouth of the
Guadalquivir, and that the lighthouse was that of
Cipiòna. Cadiz was still some eighteen miles distant.
We steered towards the city, hoping to get into
the harbour before dark. But the pilot was snapped
up by another vessel, and we did not get in. We
beat about during the night, and in the morning
found ourselves about fifteen miles from Cadiz. The
sun rose behind the city, and we steered straight into
the light. The three-towered cathedral stood in the
midst, round which swarmed apparently a multitude
of chimney-stacks. A nearer approach showed the
chimneys to be small turrets. A pilot was taken on
board; for there is a dangerous shoal in the harbour.
The appearance of the town as the sun shone upon its
white and lofty walls was singularly beautiful. We
cast anchor; some officials arrived and demanded a
clean bill of health. We had none. They would
have nothing to do with us; so the yellow quarantine
flag was hoisted, and we waited for permission
to land the Cadiz party. After some hours
of delay the English consul and vice-consul came on
board, and with them a Spanish officer, ablaze with
gold lace and decorations. Under slight pressure
the requisite permission had been granted. We
landed our party, and in the afternoon weighed
anchor. Thanks to the kindness of our excellent paymaster,
I was here transferred to a roomier berth.
Cadiz soon sank beneath the sea, and we sighted
in succession Cape Trafalgar, Tarifa, and the revolving
light of Ceuta. The water was very calm,
and the moon rose in a quiet heaven. She swung
with her convex surface downwards, the common
boundary between light and shadow being almost
horizontal. A pillar of reflected light shimmered
up to us from the slightly rippled sea. I had already
noticed the phosphorescence of the water, but to-night
it was stronger than usual, especially among
the foam at the bows. A bucket let down into the
sea brought up a number of the little sparkling
organisms which cause the phosphorescence. I
caught some of them in my hand. And here an
appearance was observed which was new to most of
us, and strikingly beautiful to all. Standing at the
bow and looking forwards, at a distance of forty or
fifty yards from the ship a number of luminous
streamers were seen rushing towards us. On nearing
the vessel they rapidly turned, like a comet round
its perihelion, placed themselves side by side, and,
as parallel trails of light, kept up with the ship. One
of them placed itself right in front of the bow as a
pioneer. These comets of the sea were joined at
intervals by others. Sometimes as many as six at a
time would rush at us, bend with extraordinary
rapidity round a sharp curve, and afterwards keep us
company. Leaning over the bow, and scanning the
streamers closely, the frontal portion of each revealed
the outline of a porpoise. The rush of the creatures
through the water had started the phosphorescence,
every spark of which was converted by the motion
of the retina into a line of light. Each porpoise
was thus wrapped in a luminous sheath. The phosphorescence
did not cease at the creature’s tail, but
was carried many porpoise-lengths behind it.
To our right we had the African hills, illuminated
by the moon. Gibraltar Rock at length became
visible, but the town remained long hidden by a belt
of haze. Through this at length the brighter lamps
struggled. It was like the gradual resolution of a
nebula into stars. As the intervening depth became
gradually less the mist vanished more and
more, and finally all the lamps shone through it.
They formed a bright foil to the sombre mass of rock
above them. The sea was so calm and the scene so
lovely that Mr. Huggins and myself stayed on deck
till the ship was moored, near midnight. During
our walking to and fro a striking enlargement of
the disc of Jupiter was observed whenever the heated
air of the funnels came between us and the planet.
On passing away from the heated air, the flat dim
disc would immediately shrink to a luminous point.
The effect was one of retinal persistence. The retinal
image of the planet was set quivering in all azimuths
by the streams of heated air, describing in quick
succession minute lines of light, which summed
themselves to a disc of sensible area.
At six o’clock next morning the gun at the signal
station on the summit of the rock boomed. At eight
the band on board the ‘Trafalgar’ training-ship,
which was in the harbour, struck up the national
anthem; and immediately afterwards a crowd of
mite-like cadets swarmed up the rigging. After the
removal of the apparatus belonging to the Gibraltar
party we went on shore. Winter was in England
when we left, but here we had the warmth
of summer. The vegetation was luxuriant—palm-trees,
cactuses, and aloes, all ablaze with scarlet
flowers. A visit to the Governor was proposed, as
an act of necessary courtesy, and I accompanied Admiral
Ommaney and Mr. Huggins to the Convent, or
Government House. We sent in our cards, waited
for a time, and were then conducted by an orderly
to his Excellency. He is a fine old man, over six
foot high, and of frank military bearing. He received
us and conversed with us in a very genial
manner. He took us to see his garden, his palms,
his shaded promenades, and his orange-trees loaded
with fruit, in all of which he took manifest delight.
Evidently ‘the hero of Kars’ had fallen
upon quarters after his own heart. He appeared full
of good nature, and engaged us on the spot to dine
with him that day.
We sought the town-major for a pass to visit the
lines. While awaiting his arrival I purchased a
stock of white glass bottles, with a view to experiments
on the colour of the sea. Mr. Huggins and
myself, who wished to see the rock, were taken by
Captain Salmond to the library, where a model of
Gibraltar is kept, and where we had a capital preliminary
lesson. At the library we met Colonel
Maberly, a courteous and kindly man, who gave us
good advice regarding our excursion. He sent an
orderly with us to the entrance of the lines. The
orderly handed us over to an intelligent Irishman,
who was directed to show us everything that we
desired to see, and to hide nothing from us. We
took the ‘upper lines,’ traversed the galleries hewn
through the limestone, looked through the embrasures,
which opened like doors in the precipice,
over the hills of Spain, reached St. George’s Hall, and
went still higher, emerging on the summit of one
of the noblest cliffs I have ever seen.
Beyond were the Spanish lines, marked by a line
of white sentry-boxes; nearer were the English lines,
less conspicuously marked out; and between both
was the neutral ground. Behind the Spanish lines
was the conical hill called the Queen of Spain’s
Chair. The general aspect of Spain from the rock
is bold and rugged. Doubling back from the galleries,
we struck upwards towards the crest, reached
the signal station, where we indulged in shandy-gaff
and bread and cheese. Thence to O’Hara’s Tower,
the highest point of the rock. It was built by a
former Governor, who, forgetful of the laws of
terrestrial curvature, thought he might look from the
tower into the port of Cadiz. The tower is riven,
and may be climbed along the edges of the crack.
We got to the top of it; thence descended the
curious Mediterranean Stair—a zigzag, mostly of
steps down a steeply falling slope, amid palmetto
brush, aloes, and prickly pear.
Passing over the Windmill Hill, we were joined
at the ‘Governor’s Cottage’ by a car, and drove afterwards
to the lighthouse at Europa Point. The tower
was built, I believe, by Queen Adelaide, and it contains
a fine dioptric apparatus of the first order,
constructed by the Messrs. Chance of Birmingham.
At the appointed hour we were at the Convent.
During dinner the same genial traits which appeared
in the morning were still more conspicuous. The
freshness of the Governor’s nature showed itself
best when he spoke of his old antagonist in arms,
Mouravieff. Chivalry in war is consistent with its
stern prosecution. These two men were chivalrous,
and after striking the last blow became friends for
ever. Our kind and courteous reception at Gibraltar
is a thing to be remembered with pleasure.
On the 15th of December we committed our
selves to the Mediterranean. The views of Gibraltar
with which we are most acquainted represent it as a
huge ridge; but its aspect, end on, both from the
Spanish lines and from the other side, is truly
noble. There is a sloping bank of sand at the back
of the rock, which I was disposed to regard simply
as the débris of the limestone. I wished to let
myself down upon it, but had not the time. My
friend Mr. Busk, however, assures me that it is
silica, and that the same sand constitutes the
adjacent neutral ground. There are theories afloat
as to its having been blown from Sahara. The
Mediterranean throughout this first day, and indeed
throughout the entire voyage to Oran, was of less
deep a blue than the Atlantic. Possibly the quantity
of organisms may have modified the colour.
At night the phosphorescence was delicious, breaking
with the suddenness of a snapped spring along
the crests of the waves formed by the port and
starboard bows. Its strength was not uniform.
Having flashed brilliantly for a time, it would in
part subside, and afterwards regain its vigour.
Several large phosphorescent masses of weird appearance
also floated past.
On the morning of the 16th we sighted the fort
and lighthouse of Marsa el Kibir, and beyond them
the white walls of Oran lying in the bight of a bay,
sheltered by dominant hills. The sun was shining
brightly; during our whole voyage we had not had so
fine a day. The wisdom which had led us to choose
Oran as our place of observation seemed demonstrated.
A rather excitable pilot came on board, and
he guided us in behind the Mole, which had suffered
much damage last year from an unexplained
outburst of waves from the Mediterranean. Both
port and bow anchors were cast into deep water.
With three huge hawsers the ship’s stern was made
fast to three gun-pillars fixed in the Mole; and here
for a time the ‘Urgent’ rested from her labours.
M. Janssen, who had rendered his name celebrated
by his observations of the eclipse in India in 1868,
when he showed the solar flames to be eruptions of
incandescent hydrogen, was already encamped in
the open country about eight miles from Oran. On
the 2nd of December he had quitted Paris in a
balloon, with a strong young sailor as his assistant,
had descended near the mouth of the Loire, seen M.
Gambetta, and received from him encouragement and
aid. On the day of our arrival his encampment was
visited by Mr. Huggins, and the kind and courteous
Engineer of the Port drove me subsequently in his
own phaeton to the place. It bore the best repute as
regards freedom from haze and fog, and commanded
an open outlook, but it was inconvenient for us on
account of its distance from the ship. The place
next in repute was the railway station, between
two and three miles distant from the Mole. It was
inspected, but, being enclosed, was abandoned for an
eminence in an adjacent garden, the property of Mr.
Hinshelwood, a Scotchman who had settled some years
previously as an esparto merchant in Oran,[46] and
who in the most liberal manner placed his ground
at the disposition of the party. Here the tents were
pitched on the Saturday by Captain Salmond and his
intelligent corps of sappers, the instruments being
erected on the Monday under cover of the tents.
Close to the railway station runs a new loopholed
wall of defence, through which the highway passes
into the open country. Standing on the highway,
and looking southwards, about twenty yards to the
right is a small bastionet, intended to carry a gun or
two. Its roof I thought would form an admirable
basis for my telescope, while the view of the surrounding
country was unimpeded in all directions.
The authorities kindly allowed me the use of this
bastionet. Two men, one a blue-jacket named
Elliot, and the other a marine named Hill, were
placed at my disposal by Lieutenant Walton; and
thus aided, on Monday morning I mounted my
telescope. The instrument was new to me, and I
wished to master all the details of its manipulation.
After some hours of discipline, and as the day
was sobering towards twilight, the telescope was
dismounted and put under cover. Mr. Huggins
joined me, and we visited together the Arab quarter
of Oran. The flat-roofed houses appeared very
clean and white. The street was filled with
loiterers, and the thresholds were occupied by
picturesque groups. Some of the men are very
fine; we saw many straight, manly fellows who
must have been six foot four in height. They passed
us with perfect indifference, evincing no anger,
suspicion, or curiosity, hardly caring in fact to glance
at us as we passed. In one instance only during my
stay at Oran was I spoken to by an Arab. He was a
tall, good-humoured fellow, who came smiling up
to me, and muttered something about ‘les Anglais.’
The mixed population of Oran is picturesque in
the highest degree: the Jews, rich and poor, varying
in their costumes as their wealth varies—the
Arabs more picturesque still, and of all shades of
complexion—the negroes, the Spaniards, the French,
all grouped together, and each preserving their
own individuality, formed a picture intensely interesting
me.
On Tuesday, the 20th, I was early at the bastionet,
with the view of schooling both myself and my men.
The night had been very squally. The sergeant of
the sappers took charge of our key, and on Tuesday
morning Elliot went for it. He brought back the
intelligence that the tents had been blown down,
and the instruments overturned. Among these was
a large and valuable equatorial from the Royal
Observatory, Greenwich. It seemed hardly possible
that this instrument, with its wheels and verniers
and delicate adjustments, could have escaped uninjured
from such a fall. This, however, was the case;
and during the day all the overturned instruments
were restored to their places, and found to be in
practical working order. This and the following
day were devoted to incessant schooling. I had
come out as a general star-gazer, and not with the
intention of devoting myself to the observation of
any particular phenomenon. I wished to see the
whole—the first contact, the advance of the moon,
and the successive swallowing up of the solar spots,
the breaking of the last line of crescent by the lunar
mountains into Bailey’s beads, the advance of the
shadow through the air, the appearance of the corona
and prominences at the moment of totality, the
radiant streamers of the corona, the internal structure
of the flames, a glance through a polariscope, a
sweep round the landscape with the naked eye, the
reappearance of the solar limb through Bailey’s
beads, and, finally, the retreat of the lunar shadow
through the air.
For these observations I was provided with a
telescope of admirable definition, mounted, adjusted,
packed, and most liberally placed at my disposal by
Mr. Warren De la Rue. The telescope grasped the
whole of the sun, and a considerable portion of the
space surrounding it. But it would not take in
the probable extreme limits of the corona. For
this the ‘finder’ was suitable; but, instead of it, I had
lashed on to the large telescope a light but powerful
instrument, constructed by Ross, and lent to me
by Mr. Huggins. I was also furnished with an
excellent binocular by Mr. Dallmeyer. In fact, no
man could have been more efficiently supported
than I was. It required a strict parcelling out of
the two minutes and some seconds of totality to
embrace in them the entire series of observations.
These, while the sun remained visible, were to be
made with an unsilvered diagonal eyepiece, which
reflected but a small fraction of the sun’s light, this
fraction being still further toned down by a dark
glass. At the moment of totality the dark glass
was to be removed, and a silver reflector pushed in,
so as to get the maximum of light from the corona
and prominences. The time of totality was distributed
as follows:
| 1. Observe approach of shadow through the air: totality. |
| 2. Telescope | 30 seconds. |
| 3. Finder | 30 seconds. |
| 4. Double image prism | 15 seconds. |
| 5. Naked eye | 10 seconds. |
| 6. Finder or binocular | 20 seconds. |
| 7. Telescope | 20 seconds. |
| 8. Observe retreat of shadow. |
It was proposed to begin and end with the telescope,
so that any change in the field of view
occurring during the totality might be noticed.
Elliot stood beside me, watch in hand, and furnished
with a lantern. He called out at the end of
each interval, and I moved from telescope to finder,
from finder to polariscope, from polariscope to naked
eye, from naked eye back to finder, from finder to
telescope, abandoning the instrument finally to
observe the retreating shadow. All this we went
over twenty times, while looking at the actual sun,
and keeping him in the middle of the field. It was
my object to render the repetition of the lesson so
mechanical as to leave no room for flurry, forgetfulness,
or excitement. Volition was not to be called
upon, nor judgment exercised, but a well-beaten
path of routine was to be followed. Had the opportunity
occurred, I think the programme would have
been strictly carried out.
But the opportunity did not occur. For several
days the weather had been ill-natured. We had
wind so strong as to render the hawsers at the stern
of the ‘Urgent’ as rigid as iron, and, therefore, to
destroy the navigating lieutenant’s sleep. We had
clouds, a thunder-storm, and some rain. Still the
hope was held out that the atmosphere would
cleanse itself, and if it did we were promised an air
of extraordinary limpidity. Early on the 22nd we
were all at our posts. Spaces of blue in the early
morning gave us some encouragement, but all
depended on the relation of these spaces to the
surrounding clouds. Which of them were to grow
as the day advanced? The wind was high, and to
secure the steadiness of my instrument I was forced
to retreat behind a projection of the bastionet, place
stones upon its stand, and, further, to avail myself of
the shelter of a sail. My practised men fastened
the sail at the top, and loaded it with boulders at the
bottom. It was tried severely, but it stood firm.
The clouds and blue spaces fought for a time
with varying success. The sun was hidden and
revealed at intervals, hope oscillating in synchronism
with the changes of the sky. At the moment of
first contact a dense cloud intervened, but a minute
or two afterwards the cloud had passed, and the
encroachment of the black body of the moon was
evident upon the solar disc. The moon marched
onward, and I saw it at frequent intervals; a large
group of spots were approached and swallowed up.
Subsequently I caught sight of the lunar limb as it
cut through the middle of a large spot. The spot
was not to be distinguished from the moon, but rose
like a mountain above it. The clouds, when thin,
could be seen as grey scud drifting across the black
surface of the moon; but they thickened more and
more, and made the intervals of clearness scantier.
During these moments I watched with an interest
bordering upon fascination the march of the silver
sickle of the sun across the field of the telescope.
It was so sharp and so beautiful. No trace of the
lunar limb could be observed beyond the sun’s
boundary. Here, indeed, it could only be relieved
by the corona, which was utterly cut off by the dark
glass. The blackness of the moon beyond the sun
was, in fact, confounded with the blackness of
space.
Beside me was Elliot with the watch and
lantern, while Lieutenant Archer, of the Royal
Engineers, had the kindness to take charge of my
note-book. I mentioned, and he wrote rapidly
down, such things as seemed worthy of remembrance.
Thus my hands and mind were entirely free; but it
was all to no purpose. A patch of sunlight fell and
rested upon the landscape some miles away. It
was the only illuminated spot within view. But to
the north-west there was still a space of blue which
might reach us in time. Within seven minutes of
totality another small space towards the zenith
became very dark. The atmosphere was, as it were,
on the brink of a precipice; it was charged with
humidity, which required but a slight chill to bring
it down in clouds. This was furnished by the withdrawal
of the solar beams; the clouds did come
down, covering up the space of blue on which our
hopes had so long rested. I abandoned the telescope
and walked to and fro, like a leopard in its
cage. As the moment of totality approached, the
descent towards darkness was as obvious as a falling
stone. I looked towards a distant ridge, where I
knew the darkness would first appear. At the moment
a fan of beams, issuing from the hidden sun, was
spread out over the southern heavens. These
beams are bars of alternate light and shade, produced
in illuminated haze by the shadows of
floating cloudlets of varying density. The beams
are really parallel, but by an effect of perspective
they appear divergent, like a fan, having the sun,
in fact, for their point of intersection. The darkness
took possession of the ridge to which I have
referred, lowered upon M. Janssen’s observatory,
passed over the southern heavens, blotting out the
beams as if a sponge had been drawn across them.
It then took successive possession of three spaces of
blue sky in the south-eastern atmosphere. I again
looked towards the ridge. A glimmer as of day-dawn
was behind it, and immediately afterwards
the fan of beams which had been for more than two
minutes absent revived. The eclipse of 1870 had
ended, and, as far as the corona was concerned,
we had been defeated.
Even in the heart of the eclipse the darkness was
by no means perfect. Small print could be read.
In fact, the clouds which rendered the day a dark
one, by scattering light into the shadow, rendered
it less intense than it would have been had the
atmosphere been without cloud. In the more open
spaces I sought for stars, but could find none.
There was a lull in the wind before and after
totality, but during the totality the wind was
strong. I waited for some time on the bastionet,
hoping to get a glimpse of the moon on the opposite
border of the sun, but in vain. The clouds continued,
and some rain fell. The day brightened
somewhat afterwards, and, having packed all up, in
the sober twilight Mr. Crookes and myself climbed
the heights above the fort of Vera Cruz. From this
eminence we had a very noble view over the
Mediterranean and the flanking African hills. The
sunset was remarkable, and the whole outlook
exceedingly fine.
The able and well-instructed medical officer of
the ‘Urgent,’ Mr. Goodman, observed the following
temperatures during the progress of the eclipse:
| Hour | Deg. |
| 11.45 | 56 |
| 11.55 | 55 |
| 12.10 | 54 |
| 12.37 | 53 |
| 12.39 | 52 |
| 12.43 | 51 |
| 1.5 | 52 |
| 1.27 | 53 |
| 1.44 | 56 |
| 2.10 | 57 |
The minimum temperature occurred some minutes
after totality, when a slight rain fell.
The wind was so strong on the 23rd that Captain
Henderson would not venture out. Guided by Mr.
Goodman, I visited a cave scooped into a remarkable
stratum of shell-breccia, and, thanks to my guide,
secured specimens. Mr. Busk informs me that a
precisely similar breccia is found at Gibraltar at
approximately the same level. During the afternoon
Admiral Ommaney and myself drove to the
fort of Marsa el Kibir. The fortification is of
ancient origin, the Moorish arches being still there
in decay, but the fort is now very strong. About
four or five hundred dragoons, fine-looking men,
were looking after their horses, waiting for a lull to
enable them to embark for France. One of their
officers was wandering in a very solitary fashion over
the fort. We had some conversation with him. He
had been at Sedan, had been taken prisoner, but
had effected his escape. He shook his head when
we spoke of the termination of the war, and predicted
its long continuance. There was bitterness
in his tone as he spoke of the charges of treason
which had been so lightly levelled against French
commanders. The green waves raved round the
promontory on which the fort stands, smiting the
rocks, breaking into snow, and jumping, after
impact, to a height of a hundred feet and more into
the air. On our return our vehicle broke down
through the loss of a wheel. The Admiral went on
board, while I hung long over the agitated sea.
The little horses of Oran well merit a passing
word. Their speed and endurance, which are both
heavily drawn upon by their drivers, are extraordinary.
The wind sinking, we lifted anchor on the 24th.
For some hours we went pleasantly along; but
during the afternoon the storm revived, and it blew
heavily against us all the night. When we came
opposite the Bay of Almeria, on the 25th, the
captain turned the ship, and steered into the bay,
where, under the shadow of the Sierra Nevada, we
passed Christmas night in peace. Next morning
‘a rose of dawn’ rested on the snows of the adjacent
mountains, while a purple haze was spread over the
lower hills. I had no notion that Spain possessed
so fine a range of mountains as the Sierra Nevada.
The height is considerable, but the form also is
such as to get the maximum of grandeur out of the
height. We got away at eight A.M., passing for a
time through shoal water, the bottom of which had
been evidently stirred up. The adjacent land
seemed eroded in a remarkable manner. Doubtless
it has its times of flood, which excavate these
valleys and ravines, and leave those singular ridges
behind. Towards evening I climbed the mainmast,
and, standing on the crosstrees, saw the sun set
amid a blaze of fiery clouds. The wind was strong
and bitterly cold, and I was glad to return to
the deck along a rope which stretched from the
mast-head to the ship’s side. That night we cast
anchor beside the Mole of Gibraltar.
On the morning of the 27th, in company with
two friends, I drove to the Spanish lines, with the
view of seeing the rock from that side. It is an
exceedingly noble mass. The Peninsular and Oriental
mail-boat had been signalled and had come.
Heavy duties called me homeward, and by transferring
myself from the ‘Urgent’ to the mail-steamer
I should gain three days. I hired a boat,
rowed to the steamer, learned that she was to start
at one, and returned with all speed to the ‘Urgent.’
Making known to Captain Henderson my wish to
get away, he expressed doubts as to the possibility
of reaching the mail-steamer in time. With his
accustomed kindness, he, however, placed a boat at
my disposal. Four hardy fellows and one of the
ship’s officers jumped into it; my luggage, hastily
thrown together, was tumbled in afterwards, and we
were immediately on our way. We had nearly four
miles to row in about twenty minutes; but we
hoped the mail-boat might not be punctual. For a
time we watched her anxiously; there was no motion;
we came nearer, but the flags were not yet hauled
in. The men put forth all their strength, animated
by the exhortations of the officer at the helm. The
roughness of the sea rendered their efforts to some
extent nugatory: still we were rapidly approaching
the steamer. At length she moved, punctually
almost to the minute, at first slowly, but soon with
quickened pace. We turned to the left, so as to
cut across her bows. Five minutes’ pull would have
brought us up to her. The officer waved his cap
and I my hat. ‘If they could only see us, they
might back to us in a moment.’ But they did not
see us, or if they did, they paid no attention to us.
I returned to the ‘Urgent,’ discomfited, but grateful
to the fine fellows who had wrought so hard to carry
out my wishes.
Glad of the quiet, in the sober afternoon I took
a walk towards Europa Point. The sky darkened,
and heavy squalls passed at intervals. Rain began
to fall, and I returned home. Private theatricals
were at the Convent, and the kind and courteous
Governor had sent cards to the eclipse party. I
failed in my duty in not going. I had heard of
St. Michael’s Cave as rivalling, if not outrivalling,
the Mammoth Cave of Kentucky. On the 28th
Messrs. Crookes, Carpenter, and myself, guided by a
military policeman who understood his work, explored
the cavern. The mouth is about 1,100 feet
above the sea. We zigzagged up to it, and first
were led into an aperture in the rock some height
above the true entrance of the cave. In this upper
cavern we saw some tall and beautiful stalactite
pillars.
The water drips from the roof charged with
bicarbonate of lime. Exposed to the air, the carbonic
acid partially escapes, and the simple carbonate
of lime, which is hardly at all soluble in water,
deposits itself as a solid, forming stalactites and
stalagmites. Even the exposure of chalk or limestone
water to the open air partially softens it. A
specimen of the Redbourne water exposed by
Messrs. Graham, Miller, and Hofmann in a shallow
basin, fell from eighteen degrees to nine degrees of
hardness. The softening process of Clark is virtually
a hastening of the natural process. Here, however,
instead of being permitted to evaporate, half the
carbonic acid is appropriated by lime, the half thus
taken up, as well as the remaining half, being precipitated.
The solid precipitate is permitted to
sink, and the clear supernatant liquid is limpid soft
water.
We returned to the real mouth of St. Michael’s
Cave, which is entered by a wicket. The floor was
somewhat muddy, and the roof and walls were wet.
Our guide took off his coat, but we did not follow
his example. We were soon in the midst of a
natural temple, where tall columns sprang complete
from floor to roof, while incipient columns were
growing to meet each other, upwards and downwards.
The water which trickles from the stalactite, after
having in part yielded up its carbonate of lime, falls
upon the floor vertically underneath, and there
builds the stalagmite. Consequently, the pillars
grow from above and below simultaneously along
the same vertical. It is easy to distinguish the
stalagmitic from the stalactitic portion of the
pillars. The former is always divided into short
segments by protuberant rings, as if deposited
periodically, while the latter presents a uniform
surface. In some cases the points of inverted cones
of stalactite rested on the centres of pillars of
stalagmite. The process of solidification and the
architecture were alike beautiful.
We followed our guide through various branches
and arms of the cave, climbed and descended steps,
halted at the edges of dark shafts and apertures,
squeezed ourselves through narrow passages, where
the sober grey of my coat suffered less than the black
of my companions’. From time to time we halted,
while Mr. Crookes illuminated with ignited magnesium
wire the roof, columns, dependent spears, and
graceful drapery of the stalactite. Once, coming to
a magnificent cluster of icicle-like spears, we helped
ourselves to specimens. There was some difficulty
in detaching the more delicate ones, their fragility
was so great. A consciousness of vandalism which
smote me at the time haunts me still; for, though
our requisitions were moderate, this beauty ought
not to be at all invaded. Pendent from the roof in
their natural habitat, nothing can exceed their
delicate beauty; they live, as it were, surrounded
by organic connections. In London they are curious,
but not beautiful. Of gathered shells Emerson
writes:
I wiped away the weeds and foam,
And brought my sea-born treasures home:
But the poor, unsightly, noisome things
Had left their beauty on the shore,
With the sun, and the sand, and the wild uproar.
The promontory of Gibraltar is so burrowed with
caverns that it has been called the Hill of Caves.
They are apparently related to the geologic disturbances
which the rock has undergone. The earliest
of these is the tilting of the once horizontal strata.
Suppose a force acting upon the promontory at its
southern extremity, near Europa Point, tending to
twist the strata in a direction opposed to that of the
hands of a watch, and suppose the rock to be of a
partially yielding character, such a force would turn
the strata into screw-surfaces, the greatest amount of
twisting being endured near the point of application
of the force. Such a twisting the rock appears to
have suffered; but instead of the twist fading gradually
and uniformly off in passing from south to
north, the want of uniformity in the material has
produced lines of dislocation where there are abrupt
changes in the amount of twist. Thus, at the
northern end of the rock the dip to the west is
nineteen degrees; in the middle hill it is thirty-eight
degrees; in the centre of the south hill, or
Sugar Loaf, it is fifty-seven degrees. At the southern
extremity of the Sugar Loaf the strata are vertical,
while further to the south they actually turn over
and dip to the east.
The rock is thus divided into three sections, separated
from each other by surfaces of dislocation,
where the rock is much wrenched and broken.
These places of dislocation are called the Northern
and Southern Quebrada, from the Spanish ‘Tierra
Quebrada,’ or broken ground; and it is at these
places that the inland caves of Gibraltar are almost
exclusively found. Based on the observations of
Dr. Falconer and himself, an excellent and most
interesting account of these caves, and of the human
remains and works of art which they contain, was
given by Mr. Busk at the meeting of the Congress
of Prehistoric Archæology at Norwich, and afterwards
printed in the ‘Transactions’ of the Congress.[47]
Long subsequently to the operation of the twisting
force just referred to, the promontory underwent
various changes of level. There are sea-terraces and
layers of shell-breccia along its flanks, and numerous
caves which, unlike the inland one, are the product
of marine erosion. The Apes’ Hill, on the African
side of the strait, Mr. Busk informs me has undergone
similar disturbances.[48]
In the harbour of Gibraltar, on the morning of
our departure, I resumed a series of observations
on the colour of the sea. On my way out I had
collected a number of specimens, with a view to
subsequent examination. But the bottles were claret
bottles, and I could by no means feel sure of their
purity. At Gibraltar, therefore, I purchased fifteen
white glass bottles, with ground glass stoppers, and
at Cadiz, thanks to the friendly guidance of Mr.
Cameron, I secured a dozen more. These seven-and-twenty
bottles were filled with water, taken at
different places between Oran and Spithead.
And here let me express my warmest acknowledgments
to Captain Henderson, the commander of
H.M.S. ‘Urgent,’ who aided me in my observations
in every possible way. Indeed, my best
thanks are due to all the officers for their unfailing
courtesy and help. The captain placed at my
disposal his own coxswain, an intelligent fellow
named Thorogood, who skilfully attached a cord to
each bottle, weighted it with lead, cast it into the sea,
and, after three successive rinsings, filled it under my
own eyes. The contact of jugs, buckets, or other
vessels was thus avoided, and even the necessity of
pouring the water out afterwards through the dirty
London air.
The mode of examination applied to these bottles
after my return to London is in some sense complementary
to that of the microscope, and may I think
materially aid enquiries conducted with that instrument.
In microscopic examination attention is
directed to a small portion of the liquid, the aim
being to detect the individual suspended particles.
In my case, a large portion of the liquid is illuminated
by a powerfully condensed beam, its general
condition being revealed through the light scattered
by suspended particles. Care is taken to defend the
eye from the access of all other light, and, thus defended,
it becomes an organ of inconceivable delicacy.
Were water of uniform density perfectly free
from suspended matter, it would, in my opinion,
scatter no light at all. The track of a luminous
beam could not, I think, be seen in such water. But
an amount of impurity so infinitesimal as to be
scarcely expressible in numbers, and the individual
particles of which are so small as wholly to elude the
microscope, may, when examined by the method
alluded to, produce not only sensible, but striking,
effects upon the eye.
The results of the examination of nineteen bottles,
filled at various places between Gibraltar and
Spithead, are here tabulated:
| No. | Locality | Colour of Sea | Appearance in Electric Beam |
| 1 | Gibraltar Harbour | Green | Thick with fine particles |
| 2 | Two miles from Gibraltar | Clearer green | Thick with very fine particles |
| 3 | Off Cabreta Point | Bright green | Still thick, but less so |
| 4 | Off Cabreta Point | Black-indigo | Much less thick, very pure |
| 5 | Off Tarifa | Undecided | Thicker than No. 4 |
| 6 | Beyond Tarifa | Cobalt-blue | Much purer than No. 5 |
| 7 | Twelve miles from Cadiz | Yellow-green | Very thick |
| 8 | Cadiz Harbour | Yellow-green | Exceedingly thick |
| 9 | Fourteen miles from Cadiz | Yellow-green | Thick, but less so |
| 10 | Fourteen miles from Cadiz | Bright green | Much less thick |
| 11 | Between Capes St. Mary and Vincent | Deep indigo | Very little matter, very pure |
| 12 | Off the Burlings | Strong green | Thick with fine matter |
| 13 | Beyond the Burlings | Indigo | Very little matter, pure |
| 14 | Off Cape Finisterre | Undecided | Less pure |
| 15 | Bay of Biscay | Black-indigo | Very little matter, very pure |
| 16 | Bay of Biscay | Indigo | Very fine matter, Iridescent |
| 17 | Off Ushant | Dark green | A good deal of matter |
| 18 | Off St. Catherine’s | Yellow green | Exceedingly thick |
| 19 | Spithead | Green | Exceedingly thick |
Here, in the first instance, we have three specimens
of water, described as green, a clearer green,
and bright green, taken in Gibraltar Harbour, at a
point two miles from the harbour, and off Cabreta
Point. The home examination showed that the
first was thick with suspended matter, the second
less thick, and the third still less thick. Thus
the green brightened as the suspended matter became
less.
Previous to the fourth observation our excellent
navigating lieutenant, Mr. Brown, steered along
the coast, thus avoiding the adverse current which
sets in through the Strait of Gibraltar from the
Atlantic to the Mediterranean. He was at length
forced to cross the boundary of the Atlantic current,
which was defined with extraordinary sharpness. On
the one side of it the water was a vivid green, on the
other a deep blue. Standing at the bow of the ship,
a bottle could be filled with blue water, while at the
same moment a bottle cast from the stern could be
filled with bright green water. Two bottles were
secured, one on each side of this remarkable boundary.
In the distance the Atlantic had the hue
called ultramarine; but looked fairly down upon, it
was of almost inky blackness—black qualified by a
trace of indigo.
What change does the home examination here
reveal? In passing to indigo, the water becomes
suddenly augmented in purity, the suspended matter
has become suddenly less. Off Tarifa, the deep
indigo disappears, and the sea is undecided in colour.
Accompanying this change, we have a rise in the
quantity of suspended matter. Beyond Tarifa, we
change to cobalt-blue, the suspended matter falling
at the same time in quantity. This water is distinctly
purer than the green. We approach Cadiz,
and at twelve miles from the city get into yellow-green
water; this the London examination shows to
be thick with suspended matter. The same is true
of Cadiz Harbour, and also of a point fourteen miles
from Cadiz in the homeward direction. Here there
is a sudden change from yellow-green to a bright
emerald-green, and accompanying the change a
sudden fall in the quantity of suspended matter.
Between Cape St. Mary and Cape St. Vincent the
water changes to the deepest indigo. In point of
purity, this indigo water is shown by the home examination
to transcend the emerald-green water.
We now reach the remarkable group of rocks
called the Burlings, and find the water between the
shore and the rocks a strong green; the home examination
shows it to be thick with fine matter. Fifteen
or twenty miles beyond the Burlings we come again
into indigo water, from which the suspended matter
has in great part disappeared. Off Cape Finisterre,
about the place where the ‘Captain’ went down, the
water becomes green, and the home examination
pronounces it to be thicker. Then we enter the Bay
of Biscay, where the indigo resumes its power, and
where the home examination shows the greatly augmented
purity of the water. A second specimen of
water taken from the Bay of Biscay held in suspension
fine particles of a peculiar kind; the size of them
was such as to render the water richly iridescent. It
showed itself green, blue, or salmon colour, according
to the direction of the line of vision. Finally,
we come to our last two bottles, the one taken opposite
St. Catherine’s lighthouse, in the Isle of Wight,
the other at Spithead. The sea at both these places
was green, and both specimens, as might be expected,
were pronounced by the home examination to be
thick with suspended matter.
Two distinct series of observations are here referred
to—the one consisting of direct observations
of the colour of the sea, conducted during the
voyage from Gibraltar to Portsmouth; the other
conducted in the laboratory of the Royal Institution.
And here it is to be noted that in the home
examination I never knew what water I had in my
hands. The labels, which had written upon them
the names of the localities, had been tied up, all
information regarding the source of the water being
thus precluded. The bottles were simply numbered,
and not till all the waters had been examined were
the labels opened, and the locality and sea-colour
corresponding to the various specimens ascertained.
I must, therefore, have been perfectly unbiassed in
my home observations, and they, I think, clearly
establish the association of the green colour of sea-water
with fine suspended matter, and the association
of the ultramarine colour, and more especially of
the black-indigo hue of sea-water, with the comparative
absence of such matter.
What, in the first place, is the cause of the dark
hue of the deep ocean?[49] A preliminary remark or
two will clear our way towards an explanation.
Colour resides in white light, appearing generally
when any constituent of the white light is withdrawn.
The hue of a purple liquid, for example,
is immediately accounted for by its action on a
spectrum. It cuts out the yellow and green, and
allows the red and blue to pass through. The
blending of these two colours produces the purple.
But while the liquid attacks with special energy the
yellow and green colours, it enfeebles the whole
spectrum; and by increasing the thickness of the
stratum we absorb the whole of the light. The
colour of a blue liquid is similarly accounted for.
It first extinguishes the red; then, as the thickness
augments, it attacks the orange, yellow, and green
in succession; the blue alone finally remaining.
But even it might be extinguished by a sufficient
depth of liquid.
And now we are prepared for a brief, but tolerably
complete, statement of the action of sea-water upon
light, to which it owes its darkness. The spectrum
embraces three classes of rays—the thermal, the
visual, and the chemical. These divisions overlap
each other; the thermal rays are in part visual, the
visual rays in part chemical, and vice versâ. The
vast body of thermal rays is beyond the red, being
invisible. These rays are attacked with exceeding
energy by water. They are absorbed close to the
surface of the sea, and are the great agents in
evaporation. At the same time the whole spectrum
suffers enfeeblement; water attacks all its rays, but
with different degrees of energy. Of the visual rays,
the red are attacked first, and first extinguished.
While the red is disappearing the remaining colours
are enfeebled. As the solar beam plunges deeper into
the sea, orange follows red, yellow follows orange,
green follows yellow, and the various shades of blue,
where the water is deep enough, follow green.
Absolute extinction of the solar beam would be the
consequence if the water were deep and uniform;
and if it contained no suspended matter, such
water would be as black as ink. A reflected glimmer
of ordinary light would reach us from its surface,
as it would from the surface of actual ink; but
no light, hence no colour, would reach us from
the body of the water.
In very clear and very deep sea-water this condition
is approximately fulfilled, and hence the
extraordinary darkness of such water. The indigo,
to which I have already referred, is, I believe, to be
ascribed in part to the suspended matter, which is
never absent, even in the purest natural water, and
in part to the slight reflection of the light from the
limiting surfaces of strata of different densities. A
modicum of light is thus thrown back to the eye
before the depth necessary to absolute extinction
has been attained. An effect precisely similar occurs
under the moraines of the Swiss glaciers. The ice
here is exceptionally compact, and, owing to the
absence of the internal scattering common in bubbled
ice, the light plunges into the mass, is extinguished,
and the perfectly clear ice presents an appearance of
pitchy blackness.[50]
The green colour of the sea when it contains
matter in a state of mechanical suspension has now
to be accounted for, and here, again, let us fall back
upon the sure basis of experiment. A strong white
dinner-plate was surrounded securely by cord, and
had a lead weight fastened to it. Fifty or sixty
yards of strong hempen line were attached to the
plate. With it in his hand, my assistant, Thorogood,
occupied a boat fastened as usual to the davits of
the ‘Urgent,’ while I occupied a second boat nearer
to the stern of the ship. He cast the plate as a
mariner heaves the lead, and by the time it had
reached me it had sunk a considerable depth in the
water. In all cases the hue of this plate was green:
even when the sea was of the darkest indigo, the
green was vivid and pronounced. I could notice
the gradual deepening of the colour as the plate
sank, but at its greatest depth in indigo water the
colour was still a blue-green.[51]
Other observations confirmed this one. The
‘Urgent’ is a screw steamer, and right over the
blades of the screw was an orifice called the screw-well,
through which one could look from the poop
down upon the screw. The surface glimmer which
so pesters the eye was here in a great measure
removed. Midway down a plank crossed the screw-well
from side to side, and on this I used to place
myself to observe the action of the screw underneath.
The eye was rendered sensitive by the moderation
of the light, and, still further to remove all disturbing
causes, Lieutenant Walton had a sail and
tarpaulin thrown over the mouth of the well.
Underneath this I perched myself and watched the
screw. In an indigo sea the play of colour was
indescribably beautiful, and the contrast between
the water which had the screw-blades for a background,
and that which had the bottom of the ocean
as a background, was extraordinary. The one was
of the most brilliant green, the other of the deepest
ultramarine. The surface of the water above the
screw-blade was always ruffled. Liquid lenses
were thus formed, by which the coloured light was
withdrawn from some places and concentrated upon
others, the colour being thus caused to flash with
metallic lustre. The screw-blades in this case
played the part of the plate in the former case,
and there were other instances of a similar kind.
The white bellies of the porpoises showed the green
hue, varying in intensity as the creatures swung to
and fro between the surface and the deeper water.
Foam, at a certain depth below the surface, is also
green. In a rough sea the light which has penetrated
the summit of a wave sometimes reaches the
eye, a beautiful green cap being thus placed upon
the wave even in indigo water.
But how is this colour to be connected philosophically
with the suspended particles? Take the
dinner-plate which showed so brilliant a green when
thrown into indigo water. Suppose it to diminish
in size until it reaches an almost microscopic magnitude.
It would still behave substantially as the
larger plate, sending to the eye its modicum of green
light. If the plate, instead of being a large coherent
mass, were ground to a powder sufficiently fine, and
in this condition diffused through the clear sea-water,
it would send green light to the eye. In fact, the
suspended particles which the home examination
reveals act in all essential particulars like the plate,
or like the screw-blades, or like the foam, or like
the bellies of the porpoises. Thus I think the
greenness of the sea is physically connected with the
matter which it holds in suspension.
We reached Portsmouth on the 5th of January
1871. There ended a voyage which, though its main
object was not realised, has left behind it pleasant
memories, both of the aspects of nature and the
genial kindliness of men.