during the war with Great Britain, the earth was searched to make
saltpetre. The guide kicks corn-cobs out of the dust where the oxen
were fed at noon, and they look nearly as fresh as ever they did. In
those frail corn-cobs and in those wheel-tracks as if the carts had
but just gone along, one seemed to come very near to the youth of the
century, almost to overtake it.
At a point in one of the great avenues, if you stop and listen, you
hear a slow, solemn ticking like a great clock in a deserted hall; you
hear the slight echo as it fathoms and sets off the silence. It is
called the clock, and is caused by a single large drop of water falling
every second into a little pool. A ghostly kind of clock there in the
darkness, that is never wound up and that never runs down. It seemed
like a mockery where time is not, and change does not come—the clock
of the dead. This sombre and mortuary cast of one's thoughts seems so
natural in the great cave, that I could well understand the emotions of
a lady who visited the cave with a party a few days before I was there.
She went forward very reluctantly from the first; the silence and the
darkness of the huge mausoleum evidently impressed her imagination, so
that when she got to the spot where the guide points out the "Giant's
Coffin," a huge, fallen rock, which in the dim light takes exactly
the form of an enormous coffin, her fear quite overcame her, and she
begged piteously to be taken back. Timid, highly imaginative people,
especially women, are quite sure to have a sense of fear in this
strange underground world. The guide told me of a lady in one of the
parties he was conducting through, who wanted to linger behind a little
all alone; he suffered her to do so, but presently heard a piercing
scream. Rushing back, he found her lying prone upon the ground in a
dead faint. She had accidentally put out her lamp, and was so appalled
by the darkness that instantly closed around her that she swooned at
once.
Sometimes it seemed to me as if I were threading the streets of some
buried city of the fore-world. With your little lantern in your hand,
you follow your guide through those endless and silent avenues,
catching glimpses on either hand of what appears to be some strange
antique architecture, the hoary and crumbling walls rising high up
into the darkness. Now we turn a sharp corner, or turn down a street
which crosses our course at right angles; now we come out into a great
circle, or spacious court, which the guide lights up with a quick-paper
torch, or a colored chemical light. There are streets above you and
streets below you. As this was a city where day never entered, no
provision for light needed to be made, and it is built one layer above
another to the number of four or five, or on the plan of an enormous
ant-hill, the lowest avenues being several hundred feet beneath the
uppermost. The main avenue leading in from the entrance is called the
Broadway, and if Broadway, New York, were arched over and reduced to
utter darkness and silence, and its roadway blocked with mounds of
earth and fragments of rock, it would, perhaps, only lack that gray,
cosmic, elemental look, to make it resemble this. A mile or so from the
entrance we pass a couple of rude stone houses, built forty or more
years ago by some consumptives, who hoped to prolong their lives by a
residence in this pure, antiseptic air. Five months they lived here,
poor creatures, a half dozen of them, without ever going forth into the
world of light. But the long entombment did not arrest the disease; the
mountain did not draw the virus out, but seemed to draw the strength
and vitality out, so that when the victims did go forth into the light
and air, bleached as white as chalk, they succumbed at once, and nearly
all died before they could reach the hotel, a few hundred yards away.
Probably the prettiest thing they have to show you in Mammoth Cave is
the Star Chamber. This seems to have made an impression upon Emerson
when he visited the cave, for he mentions it in one of his essays,
"Illusions." The guide takes your lantern from you and leaves you
seated upon a bench by the wayside, in the profound cosmic darkness.
He retreats along a side alley that seems to go down to a lower level,
and at a certain point shades his lamp with his hat, so that the light
falls upon the ceiling over your head. You look up, and the first
thought is that there is an opening just there that permits you to look
forth upon the midnight skies. You see the darker horizon line where
the sky ends and the mountains begin. The sky is blue-black and is
thickly studded with stars, rather small stars, but apparently genuine.
At one point a long, luminous streak simulates exactly the form and
effect of a comet. As you gaze, the guide slowly moves his hat, and a
black cloud gradually creeps over the sky, and all is blackness again.
Then you hear footsteps retreating and dying away in the distance.
Presently all is still, save the ringing in your own ears. Then after
a few moments, during which you have sat in a silence like that of
the interstellar spaces, you hear over your left shoulder a distant
flapping of wings, followed by the crowing of a cock. You turn your
head in that direction and behold a faint dawn breaking on the horizon.
It slowly increases till you hear footsteps approaching, and your dusky
companion, playing the part of Apollo, with lamp in hand ushers in the
light of day. It is rather theatrical, but a very pleasant diversion
nevertheless.
Another surprise was when we paused at a certain point, and the guide
asked me to shout or call in a loud voice. I did so without any unusual
effect following. Then he spoke in a very deep bass, and instantly the
rocks all about and beneath us became like the strings of an Æolian
harp. They seemed transformed as if by enchantment. Then I tried, but
did not strike the right key; the rocks were dumb; I tried again, but
got no response; flat and dead the sounds came back as if in mockery;
then I struck a deeper bass, the chord was hit, and the solid walls
seemed to become as thin and frail as a drum-head or as the frame of a
violin. They fairly seemed to dance about us, and to recede away from
us. Such wild, sweet music I had never before heard rocks discourse.
Ah, the magic of the right key! "Why leap ye, ye high hills?" why,
but that they had been spoken to in the right voice? Is not the whole
secret of life to pitch our voices in the right key? Responses come
from the very rocks when we do so. I thought of the lines of our poet
of Democracy:—
"Surely, whoever speaks to me in the right voice, him or her I
shall follow,
As the water follows the moon, silently, with fluid steps,
anywhere around the globe."
Where we were standing was upon an arch over an avenue which crossed
our course beneath us. The reverberations on Echo River, a point I did
not reach, can hardly be more surprising, though they are described as
wonderful.
There are four or five levels in the cave, and a series of avenues upon
each. The lowest is some two hundred and fifty feet below the entrance.
Here the stream which has done all this carving and tunneling has got
to the end of its tether. It is here on a level with Green River in the
valley below and flows directly into it. I say the end of its tether,
though if Green River cuts its valley deeper, the stream will, of
course, follow suit. The bed of the river has probably, at successive
periods, been on a level with each series of avenues of the cave. The
stream is now doubtless but a mere fraction of its former self. Indeed,
every feature of the cave attests the greater volume and activity of
the forces which carved it, in the earlier geologic ages. The waters
have worn the rock as if it were but ice. The domes and pits are carved
and fluted in precisely the way dripping water flutes snow or ice.
The rainfall must have been enormous in those early days, and it must
have had a much stronger and sharper tooth of carbonic acid gas than
now. It has carved out enormous pits with perpendicular sides, two or
three hundred feet deep. Goring Dome I remember particularly. You put
your head through an irregularly shaped window in the wall at the side
of one of the avenues, and there is this huge shaft or well, starting
from some higher level and going down two hundred feet below you. There
must have been such wells in the old glaciers, worn by a rill of water
slowly eating its way down. It was probably ten feet across, still
moist and dripping. The guide threw down a lighted torch, and it fell
and fell, till I had to crane my neck far out to see it finally reach
the bottom. Some of these pits are simply appalling, and where the way
is narrow have been covered over to prevent accidents.
No part of Mammoth Cave was to me more impressive than its entrance,
probably because here its gigantic proportions are first revealed to
you, and can be clearly seen. That strange colossal underworld here
looks out into the light of day, and comes in contrast with familiar
scenes and objects. When you are fairly in the cave, you cannot see it;
that is, with your aboveground eyes; you walk along by the dim light of
your lamp as in a huge wood at night; when the guide lights up the more
interesting portions with his torches and colored lights, the effect
is weird and spectral; it seems like a dream; it is an unfamiliar
world; you hardly know whether this is the emotion of grandeur which
you experience, or of mere strangeness. If you could have the light of
day in there, you would come to your senses, and could test the reality
of your impressions. At the entrance you have the light of day, and
you look fairly in the face of this underground monster, yea, into his
open mouth, which has a span of fifty feet or more, and down into his
contracting throat, where a man can barely stand upright, and where the
light fades and darkness begins. As you come down the hill through the
woods from the hotel, you see no sign of the cave till you emerge into
a small opening where the grass grows and the sunshine falls, when you
turn slightly to the right, and there at your feet yawns this terrible
pit; and you feel indeed as if the mountain had opened its mouth and
was lying in wait to swallow you down, as a whale might swallow a
shrimp. I never grew tired of sitting or standing here by this entrance
and gazing into it. It had for me something of the same fascination
that the display of the huge elemental forces of nature have, as seen
in thunder-storms, or in a roaring ocean surf. Two phœbe-birds had
their nests in little niches of the rocks, and delicate ferns and wild
flowers fringed the edges.
Another very interesting feature to me was the behavior of the cool air
which welled up out of the mouth of the cave. It simulated exactly a
fountain of water. It rose up to a certain level, or until it filled
the depression immediately about the mouth of the cave, and then
flowing over at the lowest point, ran down the hill towards Green
River, along a little watercourse, exactly as if it had been a liquid.
I amused myself by wading down into it as into a fountain. The air
above was muggy and hot, the thermometer standing at about eighty-six
degrees, and this cooler air of the cave, which was at a temperature of
about fifty-two degrees, was separated in the little pool or lakelet
which is formed from the hotter air above it by a perfectly horizontal
line. As I stepped down into it I could feel it close over my feet,
then it was at my knees, then I was immersed to my hips, then to my
waist, then I stood neck deep in it, my body almost chilled, while my
face and head were bathed by a sultry, oppressive air. Where the two
bodies of air came into contact, a slight film of vapor was formed
by condensation; I waded in till I could look under this as under a
ceiling. It was as level and as well defined as a sheet of ice on a
pond. A few moments' immersion into this aerial fountain made one turn
to the warmer air again. At the depression in the rim of the basin one
had but to put his hand down to feel the cold air flowing over like
water. Fifty yards below you could still wade into it as into a creek,
and at a hundred yards it was still quickly perceptible, but broader
and higher; it had begun to lose some of its coldness, and to mingle
with the general air; all the plants growing on the margin of the
watercourse were in motion, as well as the leaves on the low branches
of the trees near by. Gradually this cool current was dissipated and
lost in the warmth of the day.
XV
HASTY OBSERVATION
When Boswell told Dr. Johnson that while in Italy he had several times
seen the experiment tried of placing a scorpion within a circle of
burning coals, and that in every instance the scorpion, after trying
to break through the fiery circle, retired to the centre and committed
suicide by darting its sting into its head, the doctor showed the
true scientific spirit by demanding further proof of the fact. The
mere testimony of the eye under such circumstances was not enough;
appearances are often deceptive. "If the great anatomist Morgagni,"
said the doctor, "after dissecting a scorpion on which the experiment
had been tried, should certify that its sting had penetrated its head,
that would be convincing." For almost the only time in his life the
superstitious doctor showed himself, I say, a true scientist, a man
refusing to accept the truth of appearances.
But this frame of mind was not habitual to him, for the next moment
he said that swallows sleep all winter in the bed of a river or pond,
"conglobulated" into a ball. The scientific spirit would have required
him to insist upon the proof of the alleged fact in this case the same
as in the other. Has any competent observer verified this statement?
Have swallows been taken out of the mud, or been seen to throw
themselves into the water?
Albertus Magnus (1193-1280), in his book on animals, says that the eel
leaves the water in the nighttime, and invades the fields and gardens
to feed upon peas and lentils. A scientific man makes this statement,
and probably upon no stronger proof than that some eels dropped by
poachers in their hasty retreat had been found in a pea patch. If peas
had been found, and found in many cases, in the stomachs of eels, that
would have been pretty conclusive proof that eels eat peas.
The great thing in observation is not to be influenced by our
preconceived notions, or by what we want to be true, or by our fears,
hopes, or any personal element, and to see the thing just as it is. A
person who believes in ghosts and apparitions cannot be depended upon
to investigate an alleged phenomenon of this sort, because he will not
press his inquiry far enough, and will take for granted the very fact
we want proof of.
The eye does not always see what is in front of it. Indeed it might
almost be said, it sees only what is back of it, in the mind. Whenever
I have any particular subject in mind, every walk gives me new
material. If I am thinking about tree-toads, I find tree-toads. If I am
dwelling upon birds' nests, I find plenty of nests which otherwise I
should have passed by. If bird-songs occupy me, I am bound to hear some
new or peculiar note.
Every one has observed how, after he has made the acquaintance of a
new word, that word is perpetually turning up in his reading, as if it
had suddenly become the fashion. When you have a thing in mind, it is
not long till you have it in hand. Torrey and Drummond, the botanists,
were one day walking in the woods near West Point. "I have never yet
found so and so," said Drummond, naming a rare kind of moss. "Find it
anywhere," said Torrey, and stooped and picked it up at their feet.
Thoreau could pick up arrow-heads with the same ease. Many people
have the same quick eye for a four-leafed clover. I may say of myself
without vanity, that I see birds with like ease. It is no effort, I
cannot help it. Either my eye or my ear is on duty quite unbeknown to
me. When I visit my friends, I leave a trail of birds behind me, as old
Amphion left a plantation of trees wherever he sat down and played.
The scientific habit of mind leads a man to take into account all
possible sources of error in such observations. The senses are all so
easily deceived. People of undoubted veracity tell you of the strange
things they have known to rain down, or of some strange bird or beast
they have seen. But if you question them closely, you are pretty sure
to find some flaw in the observation, or some link of evidence wanting.
We are so apt to jump to conclusions; we take one or two steps in
following up the evidence, and then leap to the result that seems to be
indicated. If you find a trout in the milk, you may be justified in
jumping to a conclusion not flattering to your milkman, but if you find
angle-worms in the barrel of rain-water after a shower, you are not to
conclude that therefore they rained down, as many people think they do.
Or if after a shower in summer you find the ground swarming with little
toads, you are not to infer that the shower brought them down. I have
frequently seen large numbers of little toads hopping about after a
shower, but only in particular localities. Upon a small, gravelly hill
in the highway along which I was in the habit of walking, I have seen
them several seasons, but in no other place upon that road. Just why
they come out on such occasions is a question; probably to get their
jackets wet. There was a pond and marshy ground not far off where they
doubtless hatched. Because the frogs are heard in the marshes in spring
as soon as the ice and snow are gone, it is a popular belief that they
hibernate in these places. But the two earliest frogs, I am convinced,
pass the winter in the ground in the woods, and seek the marshes as
soon as the frost and ice are gone. I have heard the hyla pipe in a
feeble tentative manner in localities where the ground was free from
frost, while the marshes near by were yet covered with solid ice; and
in spring I have dug out another species from beneath the leaf mould
in the woods. Both these species are properly land-frogs, and only
take to the water to breed, returning again to the woods later in the
season. The same is true of the tree-frog, which passes the winter in
the ground or in hollow trees, and takes to the marshes in May to
deposit its eggs. The common bullfrog and the pickerel frog doubtless
pass the winter in the bed of ponds and streams. I think it is quite
certain that hibernating animals in the ground do not freeze, though
by no means beyond the reach of frost. The frogs, ants, and crickets
are probably protected by some sort of acid which their bodies secrete,
though this is only a guess of my own. The frog I dug out of the leaves
one spring day, while the ground above and below him was frozen hard,
was entirely free from frost, though his joints were apparently very
stiff. A friend of mine in felling some trees in winter cut through a
den of field crickets; the ground was frozen about their galleries,
but the crickets themselves, though motionless, were free from frost.
Cut the large, black tree ants out of a pine log in winter, and though
apparently lifeless, they are not frozen.
There is something in most of us that welcomes a departure from the
ordinary routine of natural causes; we like to believe that the
impossible happens; we like to see the marvelous and mysterious crop
out of ordinary occurrences. We like to believe, for instance, that
snakes can charm their prey; can exert some mysterious influence over
bird or beast at a distance of many feet, which deprives it of power to
escape. But there is probably little truth in this popular notion. Fear
often paralyzes, and doubtless this is the whole secret of the power of
snakes and cats to charm their prey. It is what is called a subjective
phenomenon; the victim is fascinated or spellbound by the sudden and
near appearance of its enemy. A sportsman, in whose veracity I have
full confidence, told me that his pointer dog had several times worked
up to a woodcock or partridge and seized it in his mouth. Of course the
dog brought no mysterious power to bear upon the bird. He could hardly
have seen the bird till he came plump upon it; he was wholly intent
upon unraveling its trail. The bird, in watching the eager motions
and the gradual approach of the dog, must have been thrown into such
a state of fear or consternation as to quite paralyze its powers, and
suffered the dog to pick it up. In the case of snakes, they doubtless
in most instances approach and seize their prey unawares. I have seen a
little snake in the woods pursue and overtake a lizard that was trying
to escape from it. There was no attempt at charming; superior speed
alone gave the victory to the snake. I have known a red squirrel to be
caught and swallowed by a black snake, but I have no belief that the
squirrel was charmed; it was more probably seized from some ambush.
One can hardly understand how a mouse can be caught by a hawk except
upon the theory that the mouse is suddenly paralyzed by fear. The
meadow mouse when exposed to view is very wary and quick in its
movements; it is nibbling grass in the meadow bottom, or clearing its
runway, or shaping its nest, when the hawk poises on wing high in the
air above it. When the hawk discovers its victim, it descends with
extended talons to the earth and seizes it. It does not drop like a
bolt from heaven; its descent, on the contrary, is quite deliberate,
and must be attended by a sound of rushing wings that ought to reach
the mouse's ear, if the form escapes its eye.
There is doubtless just as much "charming" in this case as in any
other, or when a fish hawk falls through the air and seizes a fish
near the surface in perfectly clear water—what hinders the fish from
seeing and avoiding its enemy? Apparently nothing; apparently it allows
itself to be seized. Every fisherman knows how alert most fish are, how
quickly they discover him and dart away, even when he is immediately
above them. All I contend for is that the snake, the cat, the hawk,
does not exert some mysterious power over its prey, but that its prey
in many cases loses its power to escape through fear. It is said that a
stuffed snake's skin will charm a bird as well as the live snake.
I came near reaching a hasty conclusion the other day with regard
to a chickadee's nest. The nest is in a small cavity in the limb of
a pear-tree near my study, and the birds and I are on very friendly
terms. As the nest of a pair of chickadees had been broken up here a
few seasons ago by a mouse or squirrel, I was apprehensive lest this
nest share the same fate. Hence when, one morning, the birds were
missing, and I found on inspection what appeared to be the hair of
some small animal adhering to the edges of the hole that leads to the
nest, I concluded that the birds had been cleaned out again. Later in
the day I examined the supposed hair with my pocket glass, and found
it was not hair, but some vegetable fibre. My next conclusion was
that the birds had not been molested, but that they were furnishing
their apartment, and some of the material had stuck to the door
jambs. This proved to be the correct inference. The chickadee makes
a little felt-like mat or carpet with which it covers the bottom of
the nest-cavity. A day or two later, in my vineyard near by, I found
where a piece of heavy twine that held a young grapevine to a stake had
been pulled down to the ground and picked and beaten, and parts of it
reduced to its original tow. Here, doubtless, the birds had got some of
their carpeting material.