indigo, the water becomes suddenly augmented in purity, the suspended
matter becoming 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, a further diminution of the suspended matter
being the concomitant phenomenon.
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-coloured, 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 carried out
in the laboratory of the Royal Institution. And here it is to be
noted that in the home examination I never knew what water was placed
in my hands. The labels, with the names of the localities written
upon them, had been tied up, all information regarding the source of
the water being thus held back. The bottles were simply numbered, and
not till all of them had been examined, and described, were the labels
opened, and the locality and sea-colour corresponding to the various
specimens ascertained. The home observations, therefore, must have
been perfectly unbiassed, and they clearly establish the association
of the green colour with fine suspended matter, and of the ultramarine
colour, and more especially of the black-indigo hue of the Atlantic,
with the comparative absence of such matter.
So much for mere observation; but what is the cause of the dark hue of
the deep ocean? [Footnote: A note, written to me on October 22, by my
friend Canon Kingsley, contains the following reference to this point:
'I have never seen the Lake of Geneva, but I thought of the brilliant
dazzling dark blue of the mid-Atlantic under the sunlight, and its
black-blue under cloud, both so solid that one might leap off the
sponson on to it without fear; this was to me the most wonderful thing
which I saw on my voyages to and from the West Indies.']
A preliminary remark or two will clear our way towards an explanation.
Colour resides in white light, appearing 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 such a
liquid attacks with special energy the yellow and green, it enfeebles
the whole spectrum. By increasing the thickness of the stratum we may
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 'the liquid.
And now we are prepared for a brief, but tolerably complete, statement
of that 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
versa. The vast body of thermal rays lie 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 first extinguished. 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. 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 deep sea-water this condition is approximately
fulfilled, and hence the extraordinary darkness of such water. The
indigo, already referred to, 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 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, where it is
extinguished, the perfectly clear ice presenting an appearance of
pitchy blackness. [Footnote: I learn from a correspondent that certain
Welsh tarns, which are reputed bottomless, have this inky hue.]
The green colour of the sea has now to be accounted for; and here,
again, let us fall back upon the sure basis of experiment. A strong
white dinner-plate had a lead weight securely fastened to it. Fifty
or sixty yards of strong hempen line were attached to the plate.
My assistant, Thorogood, occupied a boat, fastened as usual to the
davits of the "Urgent," while I occupied a second boat nearer the
stern of the ship. He cast the plate as a mariner heaves the lead,
and by the time it 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, even in indigo water, the colour was still
a blue-green. [Footnote: In no case, of course, is the green pure, but
a mixture of green and blue.]
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; on this I placed myself and observed the action of
the screw underneath. The eye was rendered sensitive by the
moderation of the light; and, to remove still further all disturbing
causes, Lieutenant Walton had a sail and tarpaulin thrown over the
mouth of the well. Underneath this I perched myself on the plank 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, 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 water flashing with metallic lustre. The
screw-blades in this case played the part of the dinner-plate in the
former case, and there were other instances of a similar kind. The
white bellies of 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, was also green.
In a rough sea the light which penetrated the summit of a wave
sometimes reached the eye, a beautiful green cap being thus placed
upon the wave, even in indigo water.
But how is this colour to be connected with the suspended particles?
Thus. 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 also 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 January 5, 1871. Then 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 kindliness of men.
********************
VII. NIAGARA.
[Footnote: A Discourse delivered at the Royal Institution of Great
Britain, April 4, 1873.]
It is one of the disadvantages of reading books about natural scenery
that they fill the mind with pictures, often exaggerated, often
distorted, often blurred, and, even when well drawn, injurious to the
freshness of first impressions. Such has been the fate of most of us
with regard to the Falls of Niagara. There was little accuracy in the
estimates of the first observers of the cataract. Startled by an
exhibition of power so novel and so grand, emotion leaped beyond the
control of the judgment, and gave currency to notions which have often
led to disappointment.
A record of a voyage in 1535 by a French mariner named Jacques
Cartier, contains, it is said, the first printed allusion to Niagara.
In 1603 the first map of the district was constructed by a Frenchman
named Champlain. In 1648 the Jesuit Rageneau, in a letter to his
superior at Paris, mentions Niagara as 'a cataract of frightful
height.' [Footnote: From an interesting little book presented to me at
Brooklyn by its author, Mr. Holly, some of these data are derived:
Hennepin, Kalm, Bakewell, Lyell, Hall, and others I have myself
consulted.] In the winter of 1678 and 1679 the cataract was visited
by Father Hennepin, and described in a book dedicated 'to the King of
Great Britain.' He gives a drawing of the waterfall, which shows that
serious changes have taken place since his time. He describes it as
'a great and prodigious cadence of water, to which the universe does
not offer a parallel.' The height of the fall, according to Hennepin,
was more than 600 feet. 'The waters,' he says, 'which fall from this
great precipice do foam and boil in the most astonishing manner,
making a noise more terrible than that of thunder. When the wind
blows to the south its frightful roaring may be heard for more than
fifteen leagues.' The Baron la Hontan, who visited Niagara in 1687,
makes the height 800 feet. In 1721 Charlevois, in a letter to Madame
de Maintenon, after referring to the exaggerations of his
predecessors, thus states the result of his own observations: 'For my
part, after examining it on all sides, I am inclined to think that we
cannot allow it less than 140 or 150 feet,'--a remarkably close
estimate. At that time, viz. a hundred and fifty years ago, it had
the shape of a horseshoe, and reasons will subsequently be given for
holding that this has been always the form of the cataract, from its
origin to its present site.
As regards the noise of the fall, Charlevois declares the accounts of
his predecessors, which, I may say, are repeated to the present hour,
to be altogether extravagant. He is perfectly right. The thunders of
Niagara are formidable enough to those who really seek them at the
base of the Horseshoe Fall; but on the banks of the river, and
particularly above the fall, its silence, rather than its noise, is
surprising. This arises, in part, from the lack of resonance; the
surrounding country being flat, and therefore furnishing no echoing
surfaces to reinforce the shock of the water. The resonance from the
surrounding rocks causes the Swiss Reuss at the Devil's Bridge, when
full, to thunder more loudly than the Niagara.
On Friday, November 1, 1872, just before reaching the village of
Niagara Falls, I caught, from the railway train, my first glimpse of
the smoke of the cataract. Immediately after my arrival I went with a
friend to the northern end of the American Fall. It may be that my
mood at the time toned down the impression produced by the first
aspect of this grand cascade; but I felt nothing like disappointment,
knowing, from old experience, that time and close acquaintanceship,
the gradual interweaving of mind and nature, must powerfully influence
my final estimate of the scene. After dinner we crossed to Goat
Island, and, turning to the right, reached the southern end of the
American Fall. The river is here studded with small islands. Crossing
a wooden bridge to Luna Island, and clasping a tree which grows near
its edge, I looked long at the cataract, which here shoots down the
precipice like an avalanche of foam. It grew in power and beauty.
The channel spanned by the wooden bridge was deep, and the river there
doubled over the edge of the precipice, like the swell of a muscle,
unbroken. The ledge here overhangs, the water being poured out far
beyond the base of the precipice. A space, called the Cave of the
Winds, is thus enclosed between the wall of rock and the falling
water.
Goat Island ends in a sheer dry precipice, which connects the American
and Horseshoe Falls. Midway between both is a wooden hut, the
residence of the guide to the Cave of the Winds, and from the hut a
winding staircase, called Biddle's Stair, descends to the base of the
precipice. On the evening of my arrival I went down this stair, and
wandered along the bottom of the cliff. One well-known factor in the
formation and retreat of the cataract was immediately observed. A
thick layer of limestone formed the upper portion of the cliff. This
rested upon a bed of soft shale, which extended round the base of the
cataract. The violent recoil of the water against this yielding
substance crumbles it away, undermining the ledge above, which,
unsupported, eventually breaks off, and produces the observed
recession.
At the southern extremity of the Horseshoe is a promontory, formed by
the doubling back of the gorge excavated by the cataract, and into
which it plunges. On the promontory stands a stone building, called
the Terrapin Tower, the door of which had been nailed up because of
the decay of the staircase within it. Through the kindness of Mr.
Townsend, the superintendent of Goat Island, the door was opened for
me. From this tower, at all hours of the day, and at some hours of
the night, I watched and listened to the Horseshoe Fall. The river
here is evidently much deeper than the American branch; and instead of
bursting into foam where it quits the ledge, it bends solidly over,
and falls in a continuous layer of the most vivid green. The tint is
not uniform; long stripes of deeper hue alternating with bands of
brighter colour. Close to the ledge over which the water rolls, foam
is generated, the light falling upon which, and flashing back from it,
is sifted in its passage to and fro, and changed from white to
emerald-green. Heaps of superficial foam are also formed at intervals
along the ledge, and are immediately drawn into long white striae.
[Footnote: The direction of the wind with reference to the course of a
ship may be inferred with accuracy from the foam-streaks on the
surface of the sea.] Lower down, the surface, shaken by the reaction
from below, incessantly rustles into whiteness. The descent finally
resolves itself into a rhythm, the water reaching the bottom of the
fall in periodic gushes. Nor is the spray uniformly diffused through
the air, but is wafted through it in successive veils of gauze-like
texture. From all this it is evident that beauty is not absent from
the Horseshoe Fall, but majesty is its chief attribute. The plunge of
the water is not wild, but deliberate, vast, and fascinating. From
the Terrapin Tower, the adjacent arm of the Horseshoe is seen
projected against the opposite one, midway down; to the imagination,
therefore, is left the picturing of the gulf into which the cataract
plunges.
The delight which natural scenery produces in some minds is difficult
to explain, and the conduct which it prompts can hardly be fairly
criticised by those who have never experienced it. It seems to me a
deduction from the completeness of the celebrated Thomas Young, that
he was unable to appreciate natural scenery. 'He had really,' says
Dean Peacock, 'no taste for life in the country; he was one of those
who thought that no one who was able to live in London would be
content to 'live elsewhere.' Well, Dr. Young, like Dr. Johnson, had a
right to his delights; but I can understand a hesitation to accept
them, high as they were, to the exclusion of
That o'erflowing joy which Nature yields
To her true lovers.
To all who are of this mind, the strengthening of desire on my part to
see and know Niagara Falls, as far as it is possible for them to be
seen and known, will be intelligible.
On the first evening of my visit, I met, at the head of Biddle's
Stair, the guide to the Cave of the Winds. He was in the prime of
manhood--large, well built, firm and pleasant in mouth and eye. My
interest in the scene stirred up his, and made him communicative.
Turning to a photograph, he described, by reference to it, a feat
which he had accomplished some time previously, and which had brought
him almost under the green water of the Horseshoe Fall. 'Can you lead
me there to-morrow?' I asked. He eyed me enquiringly, weighing,
perhaps, the chances of a man of light build, and with grey in his
whiskers, in such an undertaking. 'I wish,' I added, 'to see as much
of the fall as can be seen, and where you lead I will endeavour to
follow.' His scrutiny relaxed into a smile, and he said, 'Very well;
I shall be ready for you to-morrow.'
On the morrow, accordingly, I came. In the hut at the head of
Biddle's Stair I stripped wholly, and re-dressed according to
instructions,--drawing on two pairs of woollen pantaloons, three
woollen jackets, two pairs of socks, and a pair of felt shoes. Even
if wet, my guide assured me that the clothes would keep me from being
chilled; and he was right. A suit and hood of yellow oilcloth covered
all. Most laudable precautions were taken by the young assistant who
helped to dress me to keep the water out; but his devices broke down
immediately when severely tested.
We descended the stair; the handle of a pitchfork doing, in my case,
the duty of an alpenstock. At the bottom, the guide enquired whether
we should go first to the Cave of the Winds, or to the Horseshoe,
remarking that the latter would try us most. I decided on getting the
roughest done first, and he turned to the left over the stones. They
were sharp and trying. The base of the first portion of the cataract
is covered with huge boulders, obviously the ruins of the limestone
ledge above. The water does not distribute itself uniformly among
these, but seeks out channels through which it pours torrentially. We
passed some of these with wetted feet, but without difficulty. At
length we came to the side of a more formidable current. My guide
walked along its edge until he reached its least turbulent portion.
Halting, he said, 'This is our greatest difficulty; if we can cross
here, we shall get far towards the Horseshoe.'
He waded in. It evidently required all his strength to steady him.
The water rose above his loins, and it foamed still higher. He had to
search for footing, amid unseen boulders, against which the torrent
rose violently. He struggled and swayed, but he struggled
successfully, and finally reached the shallower water at the other
side. Stretching out his arm, he said to me, 'Now come on.' I looked
down the torrent, as it' rushed to the river below, which was seething
with the tumult of the cataract. De Saussure recommended the
inspection of Alpine dangers, with the view of making them familiar to
the eye before they are encountered; and it is a wholesome custom in
places of difficulty to put the possibility of an accident clearly
before the mind, and to decide beforehand what ought to be done should
the accident occur. Thus wound up in the present instance, I entered
the water. Even where it was not more than knee-deep, its power was
manifest. As it rose around me, I sought to split the torrent by
presenting a side to it; but the insecurity of the footing enabled it
to grasp my loins, twist me fairly round, and bring its impetus to
bear upon my back. Further struggle was impossible; and feeling my
balance hopelessly gone, I turned, flung myself towards the bank just
quitted, and was instantly, as expected, swept into shallower water.
The oilcloth covering was a great incumbrance; it had been made for a
much stouter man, and, standing upright after my submersion, my legs
occupied the centre of two bags of water. My guide exhorted me to try
again. Prudence was at my elbow, whispering dissuasion; but, taking
everything into account, it appeared more immoral to retreat than to
proceed. Instructed by the first misadventure, I once more entered
the stream. Had the alpenstock been of iron it might have helped me;
but, as it was, the tendency of the water to sweep it out of my hands
rendered it worse than useless. I, however, clung to it by habit.
Again the torrent rose, and again I wavered; but, by keeping the left
hip well against it, I remained upright, and at length grasped the
hand of my leader at the other side. He laughed pleasantly. The
first victory was gained, and he enjoyed it. 'No traveller,' he said,
'was ever here before.' Soon afterwards, by trusting to a piece of
drift-wood which seemed firm, I was again taken off my feet, but was
immediately caught by a protruding rock.
We clambered over the boulders towards the thickest spray, which soon
became so weighty as to cause us to stagger under its shock. For the
most part nothing could be seen; we were in the midst of bewildering
tumult, lashed by the water, which sounded at times like the cracking
of innumerable whips. Underneath this was the deep resonant roar of
the cataract. I tried to shield my eyes with my hands, and look
upwards; but the defence was useless. The guide continued to move on,
but at a certain place he halted, desiring me to take shelter in his
lee, and observe the cataract. The spray did not come so much from
the upper ledge, as from the rebound of the shattered water when it
struck the bottom. Hence the eyes could be protected from the
blinding shock of the spray, while the line of vision to the upper
ledges remained to some extent clear. On looking upwards over the
guide's shoulder I could see the water bending over the ledge, while
the Terrapin Tower loomed fitfully through the intermittent
spray-gusts. We were right under the tower. A little farther on the
cataract, after its first plunge, hit a protuberance some way down,
and flew from it in a prodigious burst of spray; through this we
staggered. We rounded the promontory on which the Terrapin Tower
stands, and moved, amid the wildest commotion, along the arm of the
Horse-hoe, until the boulders failed us, and the cataract fell into
the profound gorge of the Niagara River.