The divers descend from forty to fifty feet, seventy is the utmost

they can stand. Thirty seconds is the time they usually remain under

water, and the best cannot stay longer than a minute and a half. When

the fishing ground is reached a staging, built of the oars, is rigged

to project from the boat over the water, and to the edge of this the

diving-stones are hung, weighing from fifty to sixty pounds. The diver

stands in a stirrup upon this, or if this is wanting upon the stone

itself, holding the cord attached to it between his toes, with his

left foot he holds the net for the reception of the pearl-oysters.

Then, pressing his nostrils firmly with his left hand, and with his

right grasping the signal cord, he is let rapidly down to the bottom.

As soon as he arrives there, he removes his foot from the stone which

is immediately drawn up again. Then throwing himself flat upon the

ground, he hastily gathers into his net all the oysters within his

reach. When he feels he must return to the surface he pulls the signal

cord with a jerk, and is pulled up as quickly as possible. A good diver

seeks to avoid straining himself, and so stays under water only the

shortest time, seldom more than half a minute, but he will repeat

the operation sometimes as much as fifteen or twenty times. The work

is very distressing, the increased pressure of the water affects the

entire system, and frequently on rising to the surface the water which

runs from their ears, nose and mouth is tinged with blood. The effect

is also to induce pulmonary diseases, and the divers rarely attain old

age. Sharks are also common in these waters, and the divers are not

unfrequently destroyed by these rapacious monsters, who are the more

attracted by the fact that the divers, for their own convenience, are

naked.

The work continues until noon, when a second gun gives notice for its

cessation. The boats then return with the cargo they have gained,

and are received by the proprietors on the shore, who personally

superintend their discharge, which must be finished before dark, since

anything left over night would most certainly be stolen.

The fisheries of Ceylon were formerly very valuable, but at present

the banks show signs of exhaustion, from over-fishing most probably.

In 1798 they are said to have produced nearly a million dollars' worth

of pearls, but now they seldom yield more than a hundred thousand

dollars' worth. The inhabitants along the coast of the Bay of Bengal,

the Chinese seas, and the islands of Japan, are also engaged in the

pearl fishing. Together the yield is estimated at about four millions

of dollars.

Further west, on the Persian coast, the Arabian gulf and the Muscat

shore, as well as in the Red sea, pearls are found.

In these latter countries the pearl fishing commences in July, for

during this and the next month the sea is usually calm. When the boats

have arrived over the bed, they anchor, the water being eight or nine

fathoms deep. The divers carry their bag tied around their waists, and

plug their nostrils with cotton, then closing their mouths, are sunk by

a stone rapidly to the bottom. The pearls obtained from the fisheries

on the Arabian coast reach a value of over a million and a half of

dollars.

Pearl fishing is also carried on, on the coast of South America. Before

the Spanish conquest of Mexico the fisheries were situated between

Acapulco and the Gulf of Tehuantepec, but since that time other beds

have been found near the islands of Cubagua, Margarita and Panama. The

yield at first was so promising that flourishing cities grew up in the

vicinity of these places, and during the reign of Charles V., pearls to

the value of nearly a million of dollars were sent to Spain, but the

present yield averages only about three hundred thousand dollars.

When the oysters are taken from the boats, they are piled up on grass

mats on the shore, and left in the sun. The mollusks soon die, and

begin to decompose. In about ten days they are sufficiently putrified

to become soft. Then they are thrown into tanks of sea water, opened

and washed. The pearls which adhere to the shells are taken off with

pinchers; those that are in the body of the animal are secured by

passing its substance through a sieve, after boiling the flesh to make

it soft. The shells furnish the nacre, which is split off from the

rough outside with a sharp instrument, or the outside is dissolved from

the mother of pearl by an acid. Three kinds of mother of pearl are

known in commerce, as silver face, bastard white and bastard black;

the first is the most valuable. The pearls are the most important

part of the product. Those which adhere to the shell are always more

or less irregular in their shape, and are sold by weight. They are

called _baroques_. Those found in the body of the animal are called

_virgin pearls_, or _paragons_, and are round, oval or pyramid shaped.

These are sold generally singly; the price varying according to size,

lustre, clearness, etc. Months after the shells have been examined,

poor natives are seen diligently turning over the putrifying mass

which has been cast aside, eagerly searching for some pearl that has

been overlooked; as in our cities the ashes, barrels and gutters are

searched by the same wretched class for the refuse of luxury.

The pearls are polished by shaking them together in a bag with nacre

powder. By this process they are smoothed and polished. Then they are

assorted according to sizes by being passed through a series of copper

sieves, placed over each other, and pierced with an increasing number

of holes, growing smaller. Thus, sieve number twenty has twenty holes

in it; fifty, fifty holes, and the last of the series of twelve, one

thousand holes. The pearls retained between twenty and eighty are

called mill, and are considered to be of the first order. Those between

one hundred and eight hundred are vivadoe, and class second. Those

which pass through all but the thousand are tool, or seed pearls, and

are third. The seed pearls are sold by measure or weight. The larger

ones are drilled, strung on a white or blue silk thread, and exposed

for sale.

In the American fisheries the oysters are opened each separately with

a knife, and the animal is pressed between the thumb and finger in the

search for pearls. This process takes longer, and is not considered as

certain to find them all as that followed in the East, but the nacre

and the pearls thus taken from the live animal are fresher and more

brilliant than from those oysters which have died and decayed. Other

mollusks also furnish pearls, but not in a regular enough supply to

justify their fishing. In fact pearls are often found in our common

oysters.

[Illustration: SHARK FISHING.]

Fishing for sharks is one of the most exciting kinds of sport, and

has the further merit that its success is the destruction of the most

destructive inhabitant of the sea; a predatory robber, who spares none

that come in his way. The prey in which the shark most delights is,

however, man himself. He even manifests, according to some authorities,

a preference for Europeans over the Asiatic or the Negro races. A

shark who has once enjoyed the luxury of human flesh is said to haunt

the neighborhood where he obtained it. He follows a ship from some

instinctive feeling, and has been known to leap into a fisherman's

boat, or throw himself against a ship in an effort to reach a sailor

who had shown himself over the bulwarks. The slave ships during their

voyages were constantly followed by sharks, who battled eagerly for the

corpses of the unhappy dead which were thrown overboard. In one case it

is recorded that a corpse was hung from the yard arm, dangling twenty

feet above the water, and was devoured, limb by limb, by a shark, who

leaped that distance from the water to obtain his horrid repast.

On the African coast the negroes boldly attack the shark in his own

element. As his mouth is placed under his head, he has to turn round

before he can seize anything, and taking advantage of this, the negro

seizes the opportunity to rip him up with a sharp knife.

Shark fishing is regularly followed off the coast of Nantucket, for

their skins and the oil they furnish. The skins are used for various

purposes in the arts. In Norway and Iceland portions of the flesh are

dried, and serve as provision for the food of winter.

The persistancy with which a shark will follow a vessel at sea leads to

their frequently being caught. The hook is of iron, as thick as a man's

finger, and six or eight inches long, the point made very sharp. It is

fastened with a chain five or six feet long, to prevent the shark's

teeth from severing it. Baited with a good sized piece of pork, and

fastened to a long line, it is thrown over. Sometimes in his eagerness

to catch it the shark will jump from the water, but oftener, having

probably learned from experience something about the tricks of men, he

is more cautious in taking it. Often he will examine it, swim round

it, and manage to get it, without taking the hook also, as often as it

is offered to him rebaited. If he, however, swallows the hook with the

bait, it still requires some dexterity to catch him; the line must not

be jerked prematurely; he must be given time enough to swallow it well,

then a good jerk fixes the point of the hook, and the sport commences

for everybody but the shark. In hauling him in it is not safe to trust

only to the hook; his struggles are so violent and his strength is so

great that he may break away. Being hauled therefore to the surface,

the next thing is to get the noose of another rope round his body near

the tail, or round one of his pectoral fins. This done he may be safely

hauled on board, but even then he cannot be approached without danger,

since a blow from his tail may prove fatal. In catching sharks off the

coast of Nantucket, in smacks, the fishermen haul them to the surface

at the side of the boat, and then kill them with blows on the head

before taking them on board.

[Illustration: CUTTLE FISH MAKING HIS CLOUD.]

Among the monsters of the deep, none is more terrific in appearance

than the cuttle fish. Terrible stories have been told of the magnitude

of these sea monsters. Under the name of the Kraken marvelous tales

were told of its destruction of ships, one of them, it being said,

embracing a three-masted ship in its gigantic arms. Our illustration,

however, shows a well authenticated case of the capture of an enormous

cuttle fish. An account of the capture was made to the French Academy

of Sciences by Lieutenant Bayer, the commander of the French corvette

Alecton, who made the capture, and M. Sabin Berthelot, the French

Consul at the Canary Islands. While on her course between Teneriffe

and Madeira, the Alecton fell in with a large cuttle fish measuring

about fifty feet in length, without counting its eight arms, covered

with suckers. Its head, its largest part, measured about twenty feet

in circumference: its tail consisted of two fleshy lobes or fins. Its

weight was estimated at 4,000 pounds. Its color was brickish red, and

its flesh was soft and glutinous. The shots which were fired at it

passed through it without apparently producing any injury. After it was

thus wounded, however, the sea was observed to be covered with foam and

blood, and a strong odor of musk was smelt. Harpoons were also cast

into it, but they took no hold. Finally, however, one of the harpoons

stuck fast, and the sailors succeeded in getting a running noose round

the lower part of its body, near the tail. On attempting to haul it on

board, the rope cut it in two, the head part disappearing and the tail

portion being brought on deck.

[Illustration: IDEAL SCENE.--MONSTERS OF THE GREAT DEEP BEFORE THE

DELUGE.]

It is supposed that the animal was either sick, or exhausted from some

cause, possibly a recent struggle with some other marine monster, and

that on this account it had left its usual haunts on the rocks at the

bottom of the sea, since otherwise it would have been more active than

it was, or would have discharged the inky cloud, which the cuttle fish

has always at its disposal for avoiding its enemies.

[Illustration: RED CORAL.]

[Illustration: DREDGING.]

CHAPTER LVI.

DREDGING IN MODERN TIMES--WHAT IT HAS TAUGHT US--DEEP SEA

SOUNDINGS--FIRST ATTEMPTS--IMPLEMENTS USED FOR IT--THE CHANCE FOR

INVENTORS.

In modern times we have learned a great deal more of the ocean than the

ancients knew, from dredging. By this means we have become acquainted

not only with the outline of the bottom, but have also become

acquainted with the temperature of deep seas, with the varied forms of

animal and vegetable life which are present there, and have come to

know, with far greater certainty and completeness than ever before, the

part which the ocean has played and is still playing in the preparation

of the land.

By sounding, the ancients, of course, knew the depths of the shallow

waters along their coasts. It would be the most natural thing for a

sailor to tie a stone to a string, and let it down into the water, when

he wanted to know whether it was deep enough to float his vessel, and

the same means would also be used to discover whether there were any

sunken rocks in such harbors as he was frequenting. But the ocean,

to all antiquity, was unfathomable; they dared not attempt to cross

it, and of course did not think they could measure its depth. Long

after the ocean had been crossed by ships the belief was still current

that it was impossible to measure its depth, and this belief was made

the stronger by the unsuccessful attempts made in mid ocean to obtain

soundings with the ordinary lead and line.

Before we arrived at a positive knowledge of the depth of the ocean,

scientific men attempted to calculate it by various methods. Laplace,

calculating the mean elevation of the land, supposed the sea must be

of about equal depth. Young, drawing his deductions from the tides,

calculated the depth of the sea. This method has been recently used

to calculate the depth of the Pacific. A wave of a certain velocity

indicates water of such a depth. In the case of the earthquake of 1854,

in Japan, which caused a wave that extended to California, the rate of

its progress afforded an indication of the mean depth of the sea it

passed over, and authentic soundings taken since have confirmed the

general accuracy of the calculation.

The ordinary lead used for soundings is a pyramid of lead, the bottom

of which has a depression in it, which is filled with tallow; on

striking the bottom a little of the sand or mud adheres to this tallow

and is brought up to the surface. In this way something is learned

about the depth and bottom of the sea, but not enough to satisfy the

naturalists, who inquired whether it might not be possible to dredge

the bottom of the sea in the ordinary way, and to send down water

bottles and registering instruments to settle finally the conditions

of the deep waters, and determine with precision the composition and

temperature at great depths.

An investigation of this kind is beyond the powers of private

enterprise. It requires more power and sea skill than naturalists

usually have. It is a work for governments. That of the United States

has contributed fully its share. The coast survey has added a great

deal to our knowledge of the deep sea, and the ships of the navy took

part in the soundings by which the existence of the plateau across

the bed of the North Atlantic, which has been used for the ocean

telegraphic cable, was proved.

In 1868 the English government provided the vessels and crews for the

purpose of conducting deep sea dredgings, under the direction of Dr.

Carpenter and Mr. Wyville Thompson. These expeditions have found that

it is quite possible to work with certainty, though not with such

ease, at the depth of 600 fathoms, as at a depth of 100; and in 1869

it carried on deep sea dredging at a depth of 2,435 fathoms, 14,610

feet, or very nearly three miles, with perfect success. Dredging in

such deep water is very trying. Each haul occupied seven or eight

hours, and during the whole of this time the constant attention of

the commander was necessary, who stood with his hand on the regulator

of the accumulator, ready at any moment to ease an undue strain, by a

turn of the ship's paddles. The men, stimulated and encouraged by the

cordial interest taken by the officers in the operations, worked with a

willing spirit; but the labor of taking up three miles of rope, coming

up with a heavy strain, was very severe. The rope itself, of the very

best Italian hemp, 2 1/2 inches in circumference, with a breaking strain

of 2 1/4 tons, looked frayed out and worn, as if it could not have been

trusted to stand such an extraordinary ordeal much longer.

The ordinary deep sea lead used for soundings weighs from 80 to 120

pounds. The samples of the bottom which it brings up are marked upon

the charts as mud, shells, gravel, ooze or sand, thus 2,000 m. sh.

s. means mud, shells and sand at 2,000 fathoms; 2,050 oz. st. means

ooze and stones at 2,050 fathoms; 2,200 m. s. sh. sc. means mud,

sand, shells, and scoriæ, at 2,200 fathoms, and so on. When no bottom

is found with the lead it is entered on the chart thus:----3,200,

meaning no bottom was reached at that depth.

This method of sounding answers very well for comparatively shallow

water, but it is useless for depths much over 1,000 fathoms, or six

thousand feet. The weight is not sufficient to carry the line rapidly

and vertically to the bottom; and if a heavier weight is used, the

ordinary sounding line is not strong enough to draw up its own weight,

and that of the lead from a great depth, and so breaks. No impulse

is felt when the lead touches the bottom, and so the line continues

running out, and any attempt to stop it breaks it. In some cases the

slack of the line is carried along by currents, and in others it is

found that the line has been running out by its own weight and coiling

in a tangled mass on top of the lead.

These sources of error vitiate the results of very deep soundings. Thus

Lieutenant Walsh, of the U.S. schooner Taney, reported 34,000 feet

without touching bottom; and the U.S. brig Dolphin used a line 39,000

feet long without reaching bottom. An English ship reported 46,000 feet

in the South Atlantic and the U.S. ship Congress 50,000 feet without

touching bottom. These are, however, known to be errors, so that no

soundings are entered on charts over 4,000 feet, and few over 3,000.

The U.S. Navy introduced the first great improvement in deep soundings.

This consisted in using a heavy weight and a small line. The weight, a

32 or 68-pound shot, was rapidly run down, and when it touched bottom,

which was shown by the sudden change in the rapidity with which the

line was run out, the line was cut and the depth estimated from the

length of cord remaining on the reel. This, however, cost the loss of

the shot and the line for each sounding.

One of the first attempts at deep sea dredging was made in 1818, by

Sir John Ross, in command of the English navy vessel Isabella, on

a voyage for the exploration of Baffin's Bay with a machine of his

own invention, which he called a "deep sea clamm." It consisted of

a pair of forceps, kept apart by a bolt, and so contrived that when

the bolt struck the ground a heavy iron weight slipped down a spindle

and closed the forceps, which retained a portion of the mud, sand, or

small stones, from the bottom. With this instrument he sounded in 1,050

fathoms, and brought up six pounds of very soft mud, using a whale

line, made of the best hemp, and measuring 2 1/2 inches in circumference.

The cup lead is another invention. With this there is a pointed cup

at the bottom of the lead, fastened to it with a rod upon which a

circular plate of leather plays, serving as a cover to the cup. As it

strikes the bottom, the cup is driven in the mud, and on hauling up the

cover is pressed into the cup by the water, and brings up the mud it

contains. The objection to this is that it is too crude; in its passage

up, the water washes away the mud, so that only on an average of once

in three times does the cup come up with anything in it; and deep sea

soundings take too much time, and are too valuable, to admit so large

an average of loss.

About 1854 Mr. J. M. Brooke, of the U.S. Navy, who was at the time

associated with Prof. Maury, so well known for his labor in gathering

and diffusing a knowledge of the currents of the ocean, invented a deep

sea sounding apparatus, which is known by his name. It is still in use,

and all the more recent contrivances have been, to a great extent,

only modifications and improvements upon the original idea, that of

detatching the weight. The instrument is very simple. A 64-pound shot

is cast with a hole in it. An iron rod, with a cavity in its end, fits

loosely in the hole in the shot. Two movable arms at the top of the

rod are furnished with eyes holding ends of a sling in which the ball

hangs. The cavity at the end of the rod is furnished with tallow, and

the apparatus is let down. On reaching the bottom, the rod is forced

into the mud, the cavity becomes filled with it, and there being no

more tension, on the rope holding up the movable arms, they fall,

disengage the ends of the sling, and allow the ball to slide down the

rod. The rod is then withdrawn, carrying up the portion of the bottom

secured in the cavity at its foot, and leaving the ball on the bottom.

This apparatus costs a ball each time it is used, and brings up but a

small portion of the bottom, which is also apt to be diminished on its

way to the top, by the water it passes through.

[Illustration: STRIKING THE SEA BOTTOM. BROOK'S DEEP SEA

SOUNDING APPARATUS.]

Commander Dayman, of the English Navy, in 1857 invented an improvement

upon Mr. Brooke's original invention. He used iron wire braces to

support the sinker, as these detach more easily than slings of rope.

The shot he replaced by a cylinder of lead, as offering less surface to

the water in its descent, and he fitted the cavity in the bottom of the

rod with a valve opening inward. Commander Dayman used the apparatus,

with these modifications, in the important series of soundings he made

in the North Atlantic, while engaged in surveying the plateau for the

ocean telegraphic cable, and reports that it worked well.

[Illustration: THE BULLDOG SOUNDING MACHINE.]

The apparatus known as the bull-dog machine is an adaptation of Sir

John Ross' deep-sea clamms, together with Brooke's idea of disengaging

the weight. It was invented during the cruise of the English Navy

vessel, the Bull-dog, in 1860, and the chief credit for it belongs to

the assistant engineer during that cruise, Mr. Steil. A pair of scoops

are hinged together like a pair of scissors, the handles represented

by B. These are permanently fastened to the sounding rope, F, which

is here represented as hanging loose, by the spindle of the scoops.

Attached to this spindle is the rope, D, ending in a ring. E represents

a pair of tumbler hooks, like those used so generally. C is a heavy

weight, of iron or lead, hollow, with a hole large enough for the ring

upon D to pass through. B is an elastic ring of India rubber, fitted

to the handles of the scoops, and designed to shut them together as

soon as the weight, C, which now holds them apart, is removed. When

the bottom is reached, the scoops, open, are driven into the ground,

the tension on the rope ceases, the tumbler hooks open and release the

weight, which falls on its side, and allows the elastic ring to shut

the scoops, inclosing a portion of the bottom in which they have been

forced. The trouble with this apparatus is its complicated character;

pebbles may get in the hinge and prevent the scoops from closing. In

all apparatus to be used for such a purpose the greater the simplicity

the better, and an invention, which shall at once be simple and

effective, capable of bringing up a pound or two from the bottom at

a depth of 2,000 fathoms or more, without fail, and without too much

trouble, is still a desideratum, and its invention is well worth the

attention of the ingenious.

Another arrangement, called the Hydra sounding machine, is intended

to bring up portions of the bottom and water from the lowest strata

reached. It consists of a strong brass tube, which unscrews into four

chambers, closed with valves, opening upward, so that in the descent

the water passes through them, freely; but when it is commenced to haul

up, the pressure of the water closes the valves. This apparatus is also

furnished with weights to sink it, which are released, on reaching the

bottom, by a similar method to those described. This instrument was

used during the deep sea sounding cruise of the Porcupine, and never

once failed. Its faults are its complication, and that it brings up

only small samples of the bottom. Captain Calver, who used it, could

always, when at the greatest depths, distinctly feel the shock of the

arrest of the weight upon the bottom communicated to his hand.

[Illustration: MASSEY'S SOUNDING MACHINE.]

Various attempts have been made to construct instruments which should

accurately determine the amount of the vertical descent of the lead

by self-registering machinery. The most successful and the one most

commonly used is Massey's sounding machine. This instrument, in its

most improved form, is shown in the accompanying cut. It consists of

a heavy oval brass shield, furnished with a ring at each end of its

longer axis. To one of these a sounding rope is attached, and to the

other, the weight is fastened at about a half fathom below the shield.

A set of four brass wings or vanes are set obliquely to an axis, so

that, like a windmill or propeller wheels, it shall turn by the force

of the water as it descends. This axis communicates its motion to the

indicator, which marks the number of revolutions on the dial plate. One

of these dials marks every fathom, and the other every fifteen fathoms

of descent. This sounding machine answers very well in moderately

deep water, and is very valuable for correcting soundings by the lead

alone, where deep currents are suspected, as it is designed to register

vertical descent alone. In very deep water it is not satisfactory,

from some reason which it is difficult to determine. The most probable

explanation is that it shares the uncertainty inherent in all

instruments using metal wheel work. Their machinery seems to get jammed

in some way, under the enormous pressure of the water, at great depths.

To ascertain the surface temperature of the water of the sea is simple

enough. A bucket of water is drawn up, and a thermometer is placed in

it. With an observation of this kind the height of the thermometer in

the air should be always noted. Until very recently, however, very

little or nothing was known with any certainty about the temperature

of the sea at depths below the surface. Yet this is a field of inquiry

of very great importance in physical geography, since an accurate

determination of the temperature at different depths is certainly the

best, and frequently the only means, for determining the depth, the

width, the direction and general path of the warm ocean currents,

which are the chief agents in diffusing the equatorial heat; and more

especially of those deeper currents of cold water which return from

the poles to supply their places, and complete the watery circulation

of the globe. The main cause of this want of accurate knowledge of

deep sea temperatures is undoubtedly the defective character of the

instruments which have been hitherto employed.

The thermometer which has been generally used for making observations

on the temperature of deep water is that known as Six's self-regulating

thermometer, inclosed in a strong copper case, with valves or apertures

above and below, to allow a free passage of the water through the case

and over the face of the instrument. This registering thermometer,

consists of a glass tube, bent in the form of a U. One arm terminates

in a large bulb, entirely filled with a mixture of creosote and water.

The bend in the tube contains a column of mercury, and the other arm

ends in a small bulb, partly filled with creosote and water, but with a

large space empty, or rather filled with the vapor of the mixture and

compressed air. A small steel index with a hair tied round it, so as to

act like a spring against the side of the tube, and keep the index at

any point it may assume, lies free in either arm, among the creosote,

floating on the mercury. This thermometer gives its indications only

from the expansions and contractions of the liquid in the large full

bulb, and consequently is liable to some slight error, from the

variations of temperature upon the liquids in other parts of the tube.

When the liquid in the large bulb expands, the column of mercury is

driven upward toward the half-empty bulb, and the limb of the tube in

which it rises is graduated from below, upward, for increasing heat.

When the liquid contracts in the bulb, the mercury rises in this arm

of the tube, which is graduated from above downward, but falls in

the other arm. When the thermometer is going to be used, the steel

indices are drawn down in each limb of the tube, by a strong magnet,

till they rest, in each arm, upon the surface of the mercury. When the

thermometer is drawn up from deep water, the height at which the lower

end of the index stands in each tube indicates the limit to which the

index has been driven by the mercury, the extreme of heat or cold to

which the instrument has been exposed. Unfortunately, the accuracy of

the ordinary Six's thermometer cannot be depended upon beyond a very

limited depth, for the glass bulb which contains the expanding fluid

yields to the pressure of the water, and compressing the contained

fluid, gives an indication higher than is due to temperature alone.

This cause of error is not constant, since the amount to which the bulb

is compressed depends upon the thickness and quality of the glass.

Yet, as in thoroughly well-made thermometers, the error from pressure

is pretty constant, it has been proposed to make a scale, from an

extended series of observations, which might be used to correct the

observations, and thus closely approximate the truth.

A better plan has been proposed, and being practically applied, has

been found to work very well. This consists in incasing the full bulb

in an outer covering of glass, so that there shall be a coating of

air between the bulb and the outside coating, and that this air being

compressed by the pressure of the water outside, shall thus protect the

inside bulb. Observations taken in 1869 with thermometers constructed

in this way, as deep as 2,435 fathoms, in no instance gave the least

reason to doubt their accuracy. A modification of the metallic

thermometer, invented by Mr. Joseph Saxton, of the United States office

of weights and measures, for the use of the coast survey, may be thus

described. A ribbon of platinum and one of silver are soldered with

silver solder to an intermediate plate of gold, and this compound

ribbon is coiled round a central axis of brass, with the silver inside.

Silver is the most expansible of the metals under the influence of

heat, and platinum nearly the least. Gold holds an intermediate place,

and its intervention between the platinum and silver moderates the

strain and prevents the coil from cracking. The lower end of the coil

is fixed to the brazen axis, while the upper end is fastened to the

base of a short cylinder. Any variation of temperature causes the coil

to wind or unwind and its motion rotates the axial stem. This motion

is increased by multiplying wheels, and is registered upon the dial

of the instrument by an index, which pushes before it a registering

hand, moving with sufficient friction to retain its place, when pushed

forward. The instrument is graduated by experiment. The brass and

silver parts are thickly gilt by the electrotype process, so as to

prevent their being acted upon by the salt water.

The box in which the instrument is protected is open to admit the free

passage of the water. This instrument seems to answer very well for

moderate depths. Up to six hundred fathoms its error does not exceed

a half degree, centigrade; at 1,500 fathoms it rises however to five

degrees, quite as much as an unprotected Six thermometer, and the error

is not so constant. Instruments which depend for their accuracy upon

the working of metal machinery cannot be depended upon when subjected

to the great pressure of deep soundings.

For taking bottom temperatures at great depths, two or more of the

thermometers are lashed to the sounding line at a little distance

from each other, a few feet above the sounding instrument. The lead

is rapidly run down, and after the bottom is reached an interval of

five or ten minutes is allowed before hauling in. In taking serial

temperature soundings, which are to determine the temperature at

certain intervals of depth the thermometers are lashed to an ordinary

deep sea lead, the required quantity of line for each observation of

the series ran out, and the thermometers and lead are hove each time.

The operation is very tedious; a series of such observations in the

Bay of Biscay, where the depth was 850 fathoms and the temperature

taken for every fifty fathoms, occupied a whole day. In taking bottom

temperatures with a self-registering thermometer, the instrument

of course simply indicates the lowest temperature to which it has

been subjected, so that if the bottom stratum is warmer than any

other through which the thermometer has passed, the result would be

erroneous. This is only to be tested by serial observations; but from

these it appears, wherever they have been made, that the temperature

sinks gradually, sometimes very steadily, sometimes irregularly from

the surface to the bottom, the bottom water being always the coldest.

Several important facts of very general application in physical

geography have been settled by the deep sea temperature soundings

which have been recently made, and the theories formerly held on this

subject shown to be erroneous. It has been shown that in nature, as

in the experiments of M. Despretz, sea water does not share in the

peculiarities of fresh water, which, as has been long known, attains

its maximum density at four degrees, centigrade; but like most other

liquids increases in density to its freezing point; and it has also

been shown that, owing to the movement of great bodies of water at

different temperatures in different directions, we may have in close

proximity two ocean areas with totally different bottom climates, a

fact which, taken along with the discovery of abundant animal life at

all depths, has most important bearings upon the distribution of marine

life, and upon the interpretation of palaeontological data.

Mr. Wyville Thompson, who conducted the series of important deep

sea soundings undertaken in the Porcupine, says very truly, "It had

a strange interest to see these little instruments, upon whose

construction so much skilled labor and consideration had been lavished,

consigned to their long and hazardous journey, and their return eagerly

watched for by a knot of thoughtful men, standing, note-book in hand,

ready to register this first message, which should throw so much light

upon the physical conditions of a hitherto unknown world."

Up to the middle of the last century the little that was known of the

inhabitants of the bottom of the sea beyond low water mark, appears

to have been gathered almost entirely from the few objects thrown up

on the beaches after storms or from chance specimens brought up on

sounding lines, or by fishermen engaged in sea fishing or dredging for

oysters. From this last source, however, it was almost impossible to

obtain specimens, since the fishermen were superstitious concerning

bringing home anything but the regular objects of their industry, and

from a fear that the singular things which sometimes they drew up might

be devils in disguise, with possibly the power to injure the success

of their business, threw them again, as soon as caught, back into the

sea. Such superstitions are dying out, and in fact so singular are many

of the animals hid in the depths of the sea; their forms and general

air are so different from anything which the fishermen were used to

see, that we can hardly wonder at the fear they excited. When, however,

the attention of naturalists was turned toward the sea, they used the

dredge such as was used by the oyster fishermen, and all the dredges

now in use are simply modifications of this.

The dredge for deep sea operations is made with two scrapers, so that

it shall always present a scraping surface to the bottom, however it

may fall. The iron work should be of the very best, and weighing about

twenty pounds. The bag is about two feet deep, and is a hand-made net

of very strong twine, the meshes half an inch to the side. As so open a

net-work would let many small things through, the bottom of the bag,

to the height of about nine inches, is lined with a light open kind of

canvas, called by the sailors "bread-bag." Raw hides have been used

for making the dredge bag, but, though very strong, they are apt to

become too much so to another sense than touch. It is bad economy to

use too light a rope in such operations, and best to fasten it to only

one arm of the dredge, the eyes of the two arms being tied together

with a thinner cord. In case, then, the dredge becomes entangled at the

bottom, this cord will break first, and thus releasing one of the arms

of the dredge, may so change the direction of the strain upon the rope

as to free the dredge itself.

Dredging in deep water, that is, at depths beyond 200 fathoms, is a

matter of some difficulty, and can hardly be done with the ordinary

machinery at the disposal of amateurs. The description of the apparatus

used in the Porcupine, in 1869 and '70, on her dredging cruise in the

Bay of Biscay, will show what is necessary. These arrangements are

also shown in the cut. This vessel, a gun-boat of the English navy,

of 382 tons, was fitted out specially for this work. Amidships she

was furnished with a double cylinder donkey-engine, of about twelve

horse-power, with drums of various sizes, large and small. The large

drum was generally used, except when the cord was too heavy, and

brought up the rope at a uniform rate of more than a foot a second.

A powerful derrick projected over the port bow, and another, not so

strong, over the stern. Either of these was used for dredging, but the

one at the stern was generally used for soundings. The arrangement

for stowing away the dredge rope was such as made its manipulation

singularly easy, notwithstanding its great weight, about 5,500 pounds.

A row of some twenty large pins of iron, about two feet and a half

long, projected over one side of the quarterdeck, rising obliquely from

the top of the bulwark. Each of these held a coil of from two to three

hundred fathoms, and the rope was coiled continuously along the whole

row. When the dredge was going down, the rope was taken rapidly by the

men from these pins in succession, beginning from the one nearest the

dredging derrick, and in hauling up a relay of men carried the rope

from the drum of the donkey-engine and laid it in coils on the pins, in

reverse order. The length of the dredge rope was 3,000 fathoms, nearly

three and a half miles. Of this, 2,000 fathoms were hawser-laid, of the

best Russian hemp, 2 1/2 inches in circumference, with a breaking strain

of 2 1/4 tons. The 1,000 fathoms next the dredge were hawser laid, 2

inches in circumference. Russia hemp seems to be the best material for

such a purpose. Manilla is considerably stronger for a steady pull, but

is more likely to break at a kink.

[Illustration: THE STERN OF THE PORCUPINE.]

The frame of the largest dredge used weighed 225 pounds. The bag was

double, the outside of strong twine netting, lined with canvass. Three

sinkers, one of 100 pounds, and two of 56 pounds each, were attached

to the dredge rope at 500 fathoms from the dredge. A description of

the sounding made in the Bay of Biscay on the 22d of July, 1869, will

give an idea of the process. When the depth had been ascertained, the

dredge was let go about 4:45 p.m., the vessel drifting slowly before a

moderate breeze. At 5:50 p.m. the whole 3,000 fathoms of rope were out.

While the dredge is going down the vessel drifts gradually to leeward;

and when the whole 3,000 fathoms of rope are out, she has moved so as

to make the line from the dredge slant. The vessel now steams slowly

to windward, and is then allowed to drift again before the wind. The

tension of the vessel's motion, thus instead of acting immediately

on the dredge, now drags forward the weight, so that the dredging is

carried on from the weight and not directly from the vessel The dredge

is thus quietly pulled along, with the lip scraping the bottom, in

the position it naturally assumes from the center of weight of its

iron frame and arms. If, on the contrary, the weights were hung close

to the dredge, and the dredge was dragged directly from the vessel,

owing to the great weight and spring of the rope the arms would be

continually lifted up, and the lip of the dredge be prevented from

scraping. In very deep water this operation of steaming up to windward

until the dredge rope is nearly perpendicular, after drifting for half

an hour or so to leeward, is usually repeated three or four times.

At 8:50 p.m. hauling-in is commenced, and the donkey-engine delivers

the rope at a little more than a foot a second. A few moments before

1 o'clock in the morning the weights appear, and a little after one,

eight hours after it was cast, the dredge appears and is safely landed

on deck, having in the meantime made a journey of over eight miles.

The dredge, as the result of this haul, contained 1 1/2 hundred weight of

characteristic pale grey Atlantic ooze. The total weight brought up by

the engine was as follows:

2,000 fathoms of rope, 4,000

1,000 " " 1,500

-----

5,500

Weight of rope reduced to 1/4 in water 1,375

Dredge and bag 275

Ooze 168

Weight attached 224

-----

2,042 pounds.

In many of the dredgings at all depths it was found that while

few objects of interest were brought up within the dredge, many

echinoderms, corals and sponges came to the surface sticking to the

outside of the dredge bag, and even to the first few fathoms of the

rope. The experiment was therefore tried of fastening to a rod attached

to the bottom of the dredge bag, a half dozen swabs, such bundles of

hemp as are used on ship-board for washing the decks. The result was

marvelous; the tangled hemp brought up everything rough and movable

that came in its way, and swept the bottom of the ocean as it would

have swept the deck. So successful was this experiment, that the hempen

tangles are now regarded as an essential adjunct to the dredge, and

nearly as important as the dredge itself, and when the ground is too

rough for using the dredge, the tangles alone are used.

The mollusca have the best chance of being caught in the dredge; their

shells are comparatively small bodies mixed with the stones on the

bottom, and they enter the dredge with these. Echinoderms, corals

and sponges, on the contrary, are bulky objects, and are frequently

partially buried in the mud, or more or less firmly attached, so that

the dredge generally misses them. With the tangles it is the reverse,

the smooth heavy shells are rarely brought up, while the tangles are

frequently loaded with specimens; on one occasion not less than 20,000

examples came up on the tangles in a single haul.

In the Porcupine both derricks were furnished with accumulators, which

were found of great value. The block through which the sounding line

or dredging rope passed was not attached directly to the derrick, but

to a rope which passed through an eye at the end of the spar, and was

fixed to a bitt on the deck. On a bight of this rope, between the block

and the bitt, the accumulator was lashed. This consists of thirty or

forty, or more, vulcanized india-rubber springs, fastened together at

the two extremities, and kept free from each other by being passed

through holes in two wooden ends like barrel heads. The loop of the

rope is made long enough to permit the accumulator to stretch to double

or treble its length, but it is arrested far within its breaking point.

The accumulator is valuable in the first place as indicating roughly

the amount of strain upon the line; and in order that it may do so with

some degree of accuracy it is so arranged as to play along the derrick,

which is graduated, from trial, to the number of hundred weights of

strain indicated by the greater or less extension of the accumulator;

but its more important function is to take off the suddenness of the

strain on the line when the vessel is pitching. The friction of one or

two miles of cord in the water is so great as to prevent its yielding

to a sudden jerk, such as is given to the attached end when the vessel

rises to a sea, and the line is apt to snap.

The results which have been gained by deep sea dredging are so

important that the English Government recently fitted out another

vessel, the Challenger, for such a cruise, with every appliance. This

vessel is now due in New York.

[Illustration: AQUARIUM.]

[Illustration]

CHAPTER LVII

THE DEVELOPMENT OF SHIP BUILDING--NEW MODELS FOR SHIPS--STEAM SHIP

NAVIGATION--MONITORS--IRON-PLATED FRIGATES--TIN CLADS--RAMS--TORPEDO

BOATS--THEIR USE IN THE CONFEDERACY--LIFE RAFTS--YACHT BUILDING--OCEAN

YACHT RACE--THE COST OF A YACHT.

From the oars, which were the only means of propulsion used in the

galleys of antiquity, to the sails of a subsequent period, by which

only favoring winds could be made use of, the advance was great, but

not as great as the discovery of steam, by which in modern times the

sea is traversed with but little regard for the condition of the wind.

To suit the different means used for the propulsion of these vessels,

modifications have been made in the manner of their construction,

in their form, and with sailing ships in the arrangement of sails.

When, with the successful termination of the war of the Revolution,

the United States first took its place in the world as an independent

nation, the commercial activity which was the natural result of the

greater political freedom resulting from the issue of that contest,

found its expression first in our commerce; and the self-reliance,

which is the inevitable result of liberty; the spirit of inquiry

fostered by a departure from old methods, and the abandonment of old

traditions, were displayed in the construction, the rig and the general

air of the vessels then built, as much as in the construction of the

political organization of the new republic.

So much was this the case that American vessels became known the world

over for their trim and neat appearance. The blunt, rounded prows and

heavy sterns of the English or Dutch vessels were replaced by American

models, sharp, nothing superfluous, and riding the waters as easy as

a bird. The American clipper ships became renowned for their quick

passages, and in transporting teas from China made fortunes for their

happy owners, by bringing to the markets the first cargoes of the new

crops.

The same thing occurred when steam-vessels first began to cross the

ocean. The English in their first steamers followed the models of

their largest sailing ships. They still preserved the heavy bowsprit,

projecting twenty to thirty feet in advance of the prow, though it was

not necessary, as in their sailing ships, for balancing the pressure

of the other sails. Their steamers were therefore always heavy at the

head, and when, in a rough sea, they were driven by the power of the

engine, buried their bows in every large wave. Any one who has crossed

the Atlantic in an English steamer of twenty years ago, must have

noticed how heavily it labored in rough weather, and how the waves

broke over her bow. To take in tons of salt water when the waves ran

high, was usual; and in a passage across the Atlantic it was no rare

thing to have the salt encrusted on the smoke-stack, from the waves

which dashed over the bow and swept aft, reach a thickness of from one

to two inches.

[Illustration: PENNSYLVANIA AND OHIO ON THE STOCKS.]

The American ship-builder, however, early saw that the model of his

craft, which was to be propelled by steam, should differ from that of a

ship depending upon its sails alone, and governed himself accordingly.

He made her sharp, for speed, and ended her prow straight up and down,

as he built the steamboats for river navigation. The consequence was

that she rode dry through waves which would pour tons of salt water

upon the deck of an English model. George Steers, of New York, a genius

in naval architecture, and whose early death was deeply regretted,

was the person who did the most to bring into use the present form

used in the best models for ocean steamers. One of his first steamers,

the Adriatic, built for the Collins line, excited great attention in

Liverpool, when she first appeared there. The London _Times_ spoke of

her in leading articles, calling upon the English ship-builders to

contrast her with ships of their own construction. It spoke of how she

glided up the Mersey, making hardly a ripple from her bows, so evenly

and quietly she parted the water, while an English steamer of her size

so disturbed the stream as to bring up the mud from the bottom. The

_Times_ was also specially struck with the ease with which she was

handled, turning almost in her length, while for an English steamer

turning was an operation requiring so much more space, and making so

much more disturbance in the water. From that time to this the English

have followed the American models in the construction and equipment

of their steamers, and their example has been imitated by most other

nations.

The latest specimens of American ship building are shown in the cut

representing the Pennsylvania and Ohio on the stocks. These vessels are

the pioneers of the new line between Philadelphia and Liverpool.

Nor is this the only change which naval architecture has undergone.

The material for ship-building, especially for sea going steamers, has

in modern times come to be chiefly iron. Livingstone, in his book of

travels in Africa, tells how, when he was putting together on the banks

of one of the rivers there the pieces of a small iron steamer which

had been sent out to him from England, the natives gathered round, and

inspecting the work going on, jeered at him for thinking that a boat

built of such a material would float. Their whole experience with iron

was that it would sink. When, however, the steamer was completed and

launched, they could hardly express their astonishment at finding that

she floated.

Though every school-boy, from his text-books on natural philosophy,

can explain the reasons why a ship built of iron will float, yet our

ancestors would have considered, a proposition to construct a ship

from this material very much as the native Africans did. Even in the

construction of wooden ships, iron enters now much more than it did

formerly. The knees, or bent oak beams, by which the form of the ship

was made, have become so scarce and dear that they are now frequently

made of iron. It takes so long for an oak tree to grow, and the demand

was so great for limbs of such a natural bend as could be used for

ship-building, that even before the use of iron for such portions of a

ship, the process was in frequent use of bending the beams, or knees,

by steaming then and then subjecting them to great pressure.

Iron as a material for ships has some very great and material

advantages. It is on the whole lighter, so that an iron ship weighs

less, absolutely, than a wooden one of the same size. Then as the knees

and other timbers take up less space when made of iron, than when made

of wood, and as the thickness of the sides is much less, more space is

secured in an iron ship than in a wooden one for carrying the cargo.

Besides this, a vessel built of iron can be divided into water-tight

compartments, so that an accidental leak will damage only that portion

of the cargo contained in that compartment in which it occurs.

This method of construction is also another factor of safety in case

of accident by collision or in any other way. One compartment may be

injured so as to fill with water, while the others, being uninjured,

their buoyancy will still keep the ship afloat. An objection, however,

to the use of compartments lies in the fact that, as they must be

riveted to the sides, the rows of holes for the rivets necessarily

weaken the strength of the sides, so that a ship with compartments,

which touches on a rock or other obstacle, at one end, is more apt to

break apart than one without compartments, as the sides, unsupported by

the buoyancy of the water, have the less strength to support her weight

in the length. Still, all things considered, iron has come so much in

favor for the construction of large ships, that it is in much more

general use for that purpose than wood.

In the construction of an iron ship, the naval architect draws his

plans, and sends his construction drawings to the iron rolling mill,

where each plate is made of the exact curve and dimensions. The holes

for the rivets are punched by machinery, and the plates are then

ready to be put together. The hull of the vessel is made of iron bars

riveted together, and the plates are riveted to the iron upright ribs,

each plate overlapping the preceding. The ribs are placed from ten

to eighteen inches apart, and the whole structure is of iron. The

simplicity of the construction of an iron ship is such, that when the

plates are ready, it can be put together with wonderful rapidity.

[Illustration: MONITORS.]

[Illustration: PLANS OF THE MONITOR.]

[Illustration: ST. LOUIS.]

For constructing ships of war, iron is almost wholly used, and the

experience of our late war has almost entirely changed the methods

and theories of naval warfare. The enormous frigate, carrying a heavy

armament of numerous guns, and manned by a thousand men, has been

replaced by a small craft--so low in the water as to project above it

only a few inches, carrying but a single gun, or at most only two,

which are of very heavy calibre, and are mounted in a revolving tower

in the middle of the craft. The general description of the Monitor,

that it was a cheese-box on a raft, aptly describes their appearance.

By the introduction of the monitor as a war vessel, a complete change

was wrought in naval warfare. The large hulk of the old ships afforded

only a better target for the heavy guns of this new craft, while its

own slight projection above the water, and the fact that its engines

and propeller were covered by the water, afforded it almost absolute

security from the enemy's guns. Even if it was struck, the round shape

of its iron clad deck, and its revolving tower caused the balls to

glance off without affecting much injury. In October, 1861, forty-five

days from the laying of her keel, the St. Louis was launched, being

the first iron-clad ship owned by the United States. Other vessels

of similar design were rapidly brought to completion, and these

iron-clad river boats began their task of opening the navigation of the

Mississippi. The St. Louis was built in the city of the same name, by

Mr. James B. Eads, of that city.

[Illustration: DOUBLE ENDER.]

The cuts represent the shape of some of the iron-clads built for

service in the western rivers, where the shallowness of the stream made

it necessary that the craft should not draw too much water.

For the same reasons the "tin-clads," as they were called from the

thinness of the plates with which they were covered, were built. The

"double-enders" were also thus constructed, in order to navigate, as

necessary, either way, in the narrow and crooked streams, where our

navy performed such admirable work during the War.

The use of heavy artillery in naval warfare has also caused great

modifications to be made in the construction of other naval ships than

the monitors. To avoid the injury caused by heavy artillery, the idea

was suggested of plating them with iron. The most extensive experiments

of this kind were made in England, but not with the most gratifying

success. It was found that the iron plating rendered the ships too

heavy, if it was made thick enough to be of effective service. In a

rough sea the vessels rolled so heavily as to be nearly unmanageable,

while the weight of the plating on the sides acted with a leverage to

tear the ships in halves, so that they were considered almost unsafe.

One of them, also, on her trial trip, having capsized and sunk with

her entire crew, public confidence in them as serviceable vessels was

entirely lost; and the advantage of iron-plating large ships of war may

be still considered as an open question.

[Illustration: MINNEHAHA, OR TIN-CLAD.]

It has also been suggested that ships of war should be furnished with

a sharp beak of steel, and with such powerful engines as should secure

for them great speed, and, without trusting at all to the use of their

guns, should be used as rams to run into and crush their adversaries.

This suggestion, which is practically returning to the practice of the

ancients before the invention of either gunpowder or steam, has never

yet, however, been carried out in fact. So far, therefore, the most

serviceable modern ships of war are the monitors. The largest and most

expensive of these, the Dunderberg, was not finished until after the

war was over, and was sold, with the consent of the government, by her

builder, to Russia for $1,000,000, and crossed the Atlantic safely, a

feat which showed her to be sea-worthy, and more worthy of confidence

than any of the armored vessels built by the English Government.

In modern times attention has also been given to constructing vessels

which should be navigated under the water. Fulton, whose name is so

inseparably connected with the introduction of the steamboat, made

an attempt, the first on record, in the harbor of Brest, on the west

coast of France, in 1801, under the order of Napoleon I., to blow up

an English ship with a torpedo, a weapon of warfare which is said to

have been first suggested by Franklin, who experimented with them in

the Revolution. Fulton used, in this attempt, a submarine boat of his

own invention, the model and construction of which have never been made

public. His attempt being unsuccessful the project was abandoned, as

Napoleon withdrew his support from the scheme.

[Illustration: THE RAM IRONSIDES.]

During our late civil war, while the harbor of Charleston, South

Carolina, was blockaded by the ships of the national navy, and the

bombardment of Fort Sumter continued, attempts were made by the

besieged to destroy the blockading ships by torpedoes, which were

to be fastened by a submarine craft. One of these boats, called a

"cigar boat," though both ends were pointed, is thus described: She

was thirty feet long and six feet broad, painted a lead color. Her

propelling power consisted of a six-horse engine, geared to a shaft

turning a propeller. At her bow was an iron bowsprit, so arranged

that it could be lowered to the required depth, and at the end of

this the torpedo was secured. When afloat only about fifteen feet of

her length projected some fourteen inches above the water. For fuel

she used anthracite coal, and attained a speed of about six miles an

hour. Her tonnage was about seven or eight tons, and in this craft

Lieutenant Glassells, of Virginia, volunteered to attack the iron-clad,

the Ironsides, which was the most powerful ship at that time afloat

in the navy, rated at from three to four thousand tons. The Ironsides

was a very heavily armed ship, provided with eleven-inch guns, and

capable of delivering the heaviest broadside ever fired from a single

ship. On the night of the sixth of October, 1863, Lieutenant Glassells

set out on his expedition from one of the wharves of Charleston. The

sky was covered with clouds, and the night was very dark. His crew

consisted of a fireman and a pilot, and his offensive armament of

a torpedo, in position, and a double-barreled fowling-piece. Being

asked why he carried a gun on such an expedition, he answered: "You

know I have served in the United States navy, and I shall not attack

my old comrades like an assassin. I shall hail and fire into them,

with this, then let the torpedo do its work like an open and declared

foe." This speech is a fair specimen of the singular mixture of honor

and disloyalty which characterized the whole secession movement. This

lieutenant could desert his navy, could take up arms against his

country, but could not attack one of its ships without first giving its

crew warning.

[Illustration: TORPEDO EXPLOSION.]

The "cigar boat" steamed silently on its course until within about

fifty yards of the Ironsides, without being discovered. Everything

on the immense ship seemed as quiet as the grave. Suddenly, in the

still night, the lieutenant cries, "Ship ahoy!" "Where away?" is the

answer. "We have come to attack you," cries the lieutenant, at the same

time firing his fowling-piece, checking the engine, and directing the

torpedo. It struck, but before the "cigar boat" could retire, with a

gurgling roar it exploded. The explosion sounded like the discharge of

a submerged gun. Water mixed with flame was forced by the explosion

far up above the gunwales of the ship, and bearing up the bows of the

smaller craft, poured back in torrents through the chimney, put out

the fires, and rendered the "cigar boat" helpless.

For a moment everything on board the Ironsides was in confusion; but

the discipline of the navy was equal to the emergency. The drums beat

to quarters, the guns were manned, and the marines poured a steady fire

upon the little craft, now floating helplessly on the sea. Lieutenant

Glassells jumped into the water, to escape death from the shower of

balls; the pilot followed him, but the fireman remained at his post, as

the boat drifted away from danger. Glassells then called for help; the

marines ceased firing, and a small boat from the Ironsides rescued him

from the water. The pilot swam back to the "cigar boat" and he and the

fireman bailed her out, rekindled the fire, and escaped to Charleston.

Glassells was afterwards sent North, and under confinement his health

broke down. The Ironsides was sufficiently injured by the explosion

to be sent from her station for repairs. Had the torpedo struck her

further below, it is thought to be probable that she would have been

sunk.

Another torpedo boat was also built in Charleston, upon a different

model. This was called the "fish boat." It was built of boiler-iron,

was thirty feet long by five feet eight inches deep, and about four

and a half feet wide, amidships. Its middle section was an ellipse

flattening to a wedge shape at both ends, which were alike. It was

intended to rise or sink in the water, like a fish, and in order to

do this its specific gravity had to be kept equal that of water. In

navigating under water the boat had also to be kept upon an even keel.

On her bowsprit, which projected ten feet, the torpedo was secured, and

in order to balance the hundred and fifty pounds this weighed, an equal

amount of ballast was stowed at the stern. Ten feet from her bow she

had two iron fins, one on each side, about four feet long, seven inches

wide and three-eighths of an inch thick. These fins were fastened to an

inch rod of iron passing through water-tight fittings in her sides,

and provided with a crank inside, so that the fins could be worked

in any direction, or at any angle, forcing the craft to the surface,

or below, or forward or backward. By working them also in opposite

directions the vessel could be turned as a row-boat is by pulling with

one oar and backing water with the other. At the stern, midway between

the top and bottom, she was provided with a propeller, worked by a

shaft, fitted water-tight, and propelled by hand-power inside the hold.

On her deck were two round hatches, or man holes, about ten feet apart,

and fitted with plates of such thick glass as is used in side-walks,

for cellar lights, set in iron frames, working upon hinges, fastened on

the inside, and fitting water-tight when closed. Between these hatches

were two flexible air pipes, with air-tight valves, so that when within

a foot of the surface, by opening the valves, fresh air could be drawn

into the hold. The crew depended upon the violent action of their hats,

when the valves were open, for making a current sufficient to displace

the foul air, and bring in a supply of fresh.

When the boat was finished, in the first experiment made with her, she

carried a crew of eight men, and a shifting ballast of iron plates. She

moved from the wharf, passed down the river, just showing the tops of

the hatches, dove under a ship lying in the stream, rose on the other

side, and returned to the wharf. This was done successfully a second

time, when the chief of the crew left her for some purpose, and the

rest of the men, though unaccustomed to the work, undertook to perform

the experiment alone. She moved out, dove down, but never came up.

About a fortnight afterward she was found, raised, the dead removed,

and the whole inside disinfected, cleaned and painted white. On the

second trial she filled just as the crew had manned her, and sunk.

The captain and one other saved themselves, but the rest of the crew,

consisting of five, were drowned in her. Another crew volunteered to

man her, and on the night of the 17th of February, 1864, she set out

from Sullivan's Island, to which place she had run from her anchorage,

to attack the blockading fleet, carrying a torpedo affixed to her

bowsprit.

During the whole night the bombardment of the city was kept up, and

nothing was heard of the fish boat. The next morning a heavy fog

hung over the coast, clearing up about eight in the morning, and the

sloop-of-war Housatonic was discovered to be sunk in about six fathoms

of water, her crew swarming in her rigging for safety. The fish boat

had destroyed her, and destroyed herself in doing so. This was the

first time that she had ever been used in exploding a torpedo, and

the cause of her destruction is supposed to have been as follows: The

weight of the torpedo, on her bowsprit, was balanced by the shifting

ballast in her stern, and thus she was kept on an even keel. As soon,

however, as the torpedo struck and exploded, the balance was destroyed,

her bows were lifted by the weight in the stern, control was lost

of her, and the Housatonic, sinking from the damage done her by the

explosion, settled upon the "fish boat" and carried her and her crew to

the bottom.

Disastrous as these attempts at submarine navigation were, yet they are

the most successful yet made. We have seen else where that men have,

for other purposes than war, been able to descend under the surface

of the sea, and stay there quite a time without injury; but their

appliances are not vessels intended for navigation.

Let us turn, then, from this record of how human ingenuity has been

taxed to devise means to destroy men, to the consideration of the new

devices made for their comfort or safety in crossing the sea. One of

the most useful of these is a life raft or bolsa, one of which is

represented in our cut. This consists of three elastic cylinders, made

of india-rubber cloth, each twenty-five feet long. When empty they

are easily packed in a very small compass. For use they are blown

up, and fastened to a prepared staging. The cut represents one which

crossed the Atlantic in 1867, arriving at Southampton July 25, having

started from New York forty-three days before. She was rigged with

two masts secured to the staging, and her crew consisted of three

men, John Wilkes, George Miller and Jerry Mallene. A bellows to fill

the cylinders, should they require it, was an important item in her

cargo. The crew kept alternate watch, sleeping, by turns, in a tent

spread on the staging. Their supply of water they carried in casks. The

experiment of crossing the Atlantic was made to show the safety of a

raft thus constructed.

[Illustration: LIFE RAFT.]

For attaining speed, and thus diminishing the tedium and the risk of an

Atlantic voyage, Mr. Wynans, of Baltimore, has invented a cigar-shaped

boat, as it is called, though it is pointed at both ends. Various

causes have hitherto prevented his final experiment with his boat,

but he hopes to be able to make with it an average speed of at least

eighteen miles an hour.

Crossing the Atlantic has become so common, and sea-sickness making

the trip so disagreeable and dangerous to many people, attention has

been turned to inventing a method of construction which shall destroy

the cause for this malady, by keeping the saloon always on a level,

notwithstanding the pitching and rolling of the ship in a high sea.

Mr. Bessemer, the inventor of the new process for making steel, has

invented a boat, which he is now constructing, and which he thinks will

make it perfectly feasible to cross the Atlantic without the necessity

of paying the usual tribute to old Neptune. The general idea of his

ship may be thus described: The saloon for passengers is to be balanced

upon a frame work similar in principle to that by which the lamps on

ship-board are supported. An outer circle swings upon pivots at each

end of its diameter, and within another circle supports the lamp, which

is swung upon pivots at right angles with those in the first. However,

then, the ship may pitch or roll, the lamp remains perpendicular, the

circles adjusting themselves to meet the motion of the ship. This idea

is to be applied in the construction of the saloon, so that it will

remain constantly on a level, and as Mr. Bessemer has a plenty of money

to construct a dozen of ships for an experiment, the public may expect

before long to hear of a trial. The first ship of the kind is reported

as on the stocks, and to be rapidly approaching completion. Nor is this

the only style of ship suggested to obviate sea-sickness. A Russian,

M. Alexandroiski, proposes a new form of stationary ship-saloon, which

differs from that of Mr. Bessemer in having the cabin float in kind of

a tank placed between the engines, instead of being hung on pivots.

This invention, it is stated, has been tested by the Russian Naval

Department, and is reported to have been found entirely satisfactory,

the rolling motion of the vessel being completely counteracted. With

the success of one or the other of these plans, an ocean voyage, even

in a rough sea, will become a pleasure trip, like sailing in a painted

ship upon a painted ocean; the wildness of a storm even may become

merely an exciting spectacle, like looking at the representation of a

hurricane in a theatre, with the further advantage of having it real

and life-like.

Perhaps the change which has been brought about in our feeling with

regard to the ocean is shown more in the yachting of modern times than

in anything else. The idea of making a trip across the Atlantic is no

longer considered an almost foolhardy undertaking, but even our yachts

have made it a field for their races, and a match across the Atlantic

has become not an unusual thing. The owning of yachts has become so

general among our rich men, that yacht-building has become a regular

branch of naval architecture, and constant improvements are being

made in their models, and greater luxury displayed in their fitting

up. George Steers, who has been mentioned before for his improvements

in the model of the steamship, made his first reputation by the

construction of the yacht America, which was sent over to England, and

proved the fastest vessel in the regatta on the occasion of the first

World's Fair in London. This yacht, after her victory, was bought by an

Englishman, and never used again, being left to rot at her moorings.

However, she changed the yacht models of Europe.

[Illustration: OCEAN YACHT RACE.--THE HENRIETTA, VISTA AND FLEETWING.]

A yacht race across the Atlantic was one of the sensations of the year

1866. Three yachts entered the contest, the Henrietta, the Fleetwing

and the Vista. They started from Sandy Hook one day in December, and

though the season had been unusually stormy, and they encountered gales

almost all the way, so that frequently they were forced to sail under

bare poles, and the Fleetwing lost several of her sailors, who were

washed overboard, yet they arrived safe at Cowes on the same day, after

a fourteen days' voyage, the Henrietta winning the race by a couple

of hours. This yacht was the property of James Gordon Bennett, Jr.,

the son of the owner of the New York Herald. During the war her owner

freely offered her to the government, and she has done good service.

After the victory Mr. Bennett sold her for $15,000, and purchased the

Fleetwing for $65,000, re-christening her the Dauntless. This yacht,

in another ocean race in 1870, was beaten by the Cambria, an English

yacht. These prices show the cost of seeking one's pleasure in a yacht,

and yet it is only one item of the expense. To keep one of the vessels

costs more than the expenses of the majority of the households in the

country. A crew of five men is needed, and it is a question whether,

all things considered, more real substantial interest and enjoyment

is not taken by a lover of the sea and of sailing in an ordinary

sail-boat, which he and a friend or two are amply competent to man and

manage, than is taken by the owners of the most luxuriantly furnished

yachts in the world. As pleasure ships, however, the yacht is all that

can be desired. Many of them contain spacious saloons; their cabins are

almost always paneled in costly woods, and most luxuriantly furnished,

and even gas has been provided for them. It is estimated that the

yachts of the New York club alone have cost more than $2,000,000, and

those of the whole country about $5,000,000. Much of this is the mere

luxury of ostentation; but as the real pleasures there are in thus

visiting distant lands come to be better appreciated, much of this

foolish expenditure will be abandoned.

[Illustration]

CHAPTER LVIII.

OUR KNOWLEDGE OF THE EARTH AND SEA--HOW IT HAS INCREASED--THE

EARTH THE DAUGHTER OF THE OCEAN--THE OPINION OF SCIENCE--THE MEAN

DEPTH OF THE OCEAN--THE EXTENT OF THE OCEAN--ITS VOLUME--SPECIFIC

GRAVITY OF SEA-WATER--CONSTITUTION OF SALT-WATER--THE SILVER IN THE

SEA--THE WAVES OF THE SEA--THE CURRENTS OF THE OCEAN--THE TIDES--THE

AQUARIUM--THE COMMERCE OF MODERN TIMES--THE SPREAD OF PEACE.

In the preceding pages the facts have been given in a comprehensive

though succinct form, which enable us to see how, step by step, each

one of which became possible only when those preceding had been taken.

Mankind has gained a knowledge of the outlines of the sea; of the

form of the earth itself; of the relative positions occupied by the

water and the land; of their action upon each other, and thus the way

has been prepared by the enterprise of preceding generations for the

scientific methods of study which characterize the modern era. The

adventurous voyagers of the early times, who, daring as they were,

hardly were bold enough to venture in their open boats, propelled only

by oars, out of the sight of land, could not be expected to conceive

that it could be possible for men, like themselves, to ever become

able to construct ships such as modern nations construct, in which,

propelled by steam, voyages should be taken across oceans, and out of

sight of land, their course over the trackless waters be guided with

accuracy and certainty, to any desired point, by the compass and the

observations of the motions of the stars.

By experiment and observation the entire aspect and conception of

the ocean has been changed in modern times from that which prevailed

in antiquity, or even more recently, until within the few past

generations. Though much has been done, in the study of the ocean,

toward obtaining a proper conception of its influence in the general

economy of the globe, yet there is still much to be learned. Among

the ancients it was generally declared in their cosmogonies that the

solid portions of the world were produced by the ocean. "Water is the

chief of all," says Pindar; "the earth is the daughter of ocean," is

the mythological statement common to the primitive nations. Though this

poetical expression was merely based upon a vague tradition, and can

hardly be taken as the result of any methodical study of the earth,

yet modern science tends to show that it is really true. The ocean has

produced the solid land. The study of geology, the skilled inspection

of the various strata of the land--the rocks, sand, clay, chalk,

conglomerates--proves that the materials of the continents have been

chiefly deposited at the bottom of the sea, and raised to their present

position by the chemical or mechanical agencies which are constantly at

work in the vast laboratory of nature.

Many rocks, as for instance the granites of Scandinavia, which were

previously believed to have been projected in a molten and plastic

state from the interior of the earth, where they had been subjected

to the action of the intense heat supposed to exist in the centre

of the earth, are now supposed to be in reality ancient sedimentary

strata, slowly deposited by the sea, and upheaved by the contraction

of the crust, or by some other force of upheaval acting from the

centre. Upon the sides of mountains, or on their summits, now thousands

of feet above the level of the ocean, unquestionable traces of the

action of the sea can be found. And the scientific observer of to-day

sees all about him evidences that the immense work of the creation

of continents, commenced by the sea in the earliest periods of time,

is to-day continuing without relaxation or intermission, and with

such energy that even during the short course of a single life great

changes can be seen to have been produced. Here and there a coast,

subject to the beating of the serf, is seen to be slowly undermined,

disintegrated, worn down and carried away, while in another place the

material is deposited by the sea, and sandy beaches or promontories

are built up. New rocks also, differing in appearance and constitution

from those worn away, are formed. But beside this action of the sea

upon the coasts, in constantly changing the configuration of the land,

modern observation has shown us that animal life is an agent constantly

at work within the sea itself, in the formation of new lands. The

innumerable minute forms of life with which the sea swarms; the coral

polyps, the shells, the sponges, and the animalculæ of all kinds, are

constantly engaged in consuming the food they find, in reproducing

themselves, and in dying. From the various matters brought down to the

ocean by the rivers of the land, they secrete their shells or other

coverings; and as generation after generation they die, these falling

to the bottom form immense banks, or plains, which some future action

of upheaval will bring above the surface to form the material for new

continents or islands.

Thus while the ocean prepares the materials for the future continents

in its bosom, it also furnishes the waters which wash away the lands

already existing. To the thought of modern science the granite peaks,

the snow-clad mountains, immovable and eternal as they seem, are

constantly disintegrating, and partake, with every thing else in

creation, the eternal round of change which is constantly going on.

From the sea, by evaporation, rise the vapors which, condensing against

the sides of the mountains, form the glaciers; and these, slowly

sliding down toward the plains, are such efficient agents in wearing

away the mountains, grinding up their solid rocks and preparing the

gravel which the mountain streams distribute over the plains. From

the sea the atmosphere receives the moisture destined to return in

rain from the clouds; to feed the brooks whose union forms the rivers,

destined again to return to the sea the waters it provided, and thus

keep up, in a single, mighty and endless circulation, the waters of the

globe.

Thus to the agency of the ocean we are indebted for our rivers, which

have played such an important part in the geological history of the

earth, in the distribution of the flora and fauna of various countries,

and on the life of man himself. In the study also of the climates

of the earth, and their effects upon life, we find the ocean bears

a most important part. As the circulation of the atmosphere mingles

the heated air from the equator with that of the frozen regions of

the poles, so the currents of the ocean circulate about the earth,

blending the contrasts of climate, and making a harmonious whole of

all the different portions. Thus, instead of considering the ocean as

the barren waste of desolation it appeared to the ancients, to the

modern thinker the ocean has, layer by layer, deposited the land from

its bosom, and now by its vapors provides the rains which support

its vegetable life, upon which all other life depends, and creates

the rivers and the springs, which play such an important part in the

modification of the interior of continents, at the greatest distance

from the sea.

The mean depth of the whole mass of the ocean waters of the globe is

estimated at about three miles, since measurements have shown that the

basins of the Atlantic and Northern Pacific are deeper than this by

hundreds of thousands of fathoms. The extent covered by the surface of

the ocean has been estimated at more than 145,000,000 of square miles,

and with this estimate, the sea is calculated to form a volume of about

two and one-half million billions of cubic yards, or about the five

hundred and sixtieth part of the planet itself. The highest point of

the land raised above the level of the sea is much less elevated than

the bottom of the sea is depressed from the same level, so that the

mass of the land above this level can be estimated only at about a

fortieth part of the mass of the waters.

The specific gravity of sea water is greater than that of fresh.

This comes from the various matters which it holds in solution. This

difference varies with different seas; with the quantity of matters

held in solution; with the amount of evaporation; the size and number

of rivers flowing into the various seas; the ice melting into them; the

currents, and various other causes. The average quantity of salts held

in solution in sea water is estimated at 34.40 parts in 1,000, and this

average is the same in all seas. The quantity of common salt held in

solution is always a little more than three-quarters (75.786) of the

total mineral matter held in solution. The salt of the sea averages,

if the water is evaporated, about two inches to every fathom; so that,

were the ocean dried up, a layer of salt about two hundred and thirty

feet thick would remain on the bottom, or the whole salt of the sea

would measure more than a thousand millions of cubic miles. This vast

quantity of salt in the sea explains how the enormous beds of rock salt

were formed, when the lands now exposed were covered by the waters.

Beside the oxygen and hydrogen which constitute its waters, the sea

contains chlorine, nitrogen, carbon, bromine, iodine, fluorine,

sulphur, phosphorus, silicon, sodium, potassium, boron, aluminium,

magnesium, calcium, strontium, barium. From the various sea-weeds most

of these substances can be obtained. Copper, lead, zinc, cobalt, nickel

and manganese have also been found in their ashes. Iron has also been

obtained from sea water, and a trace of silver also is often deposited

by the magnetic current established between the sheeting of ships and

the salt water. Though only a trace is thus found, yet it has been

estimated that the whole waters of the ocean contain in solution two

million tons of silver. In the boilers of ocean steamships, which use

sea water, arsenic has also been found.

Sea water also retains dissolved air better than fresh water, and the

bulk of this in ocean water is generally greater by a third than

that found in river water. It varies from a fifth to a thirtieth, and

gradually increases from the surface to a depth of about three hundred

and twenty-five to three hundred and eighty fathoms. The uniformity

in the constitution of the waters of the sea is chiefly caused by the

action of the waves, which finally mix and mingle the waters into

a homogeneous mass. The waves of the sea are caused chiefly by the

action of the wind, and the effect continues even after the wind has

ceased. One of the grandest spectacles at sea is offered by the regular

movement of the waves in perfectly calm weather, when not a breath of

air stirs the sails. During to the Autumnal calm under the Tropic of

Cancer, these waves appear with astonishing regularity at intervals of

two hundred to three hundred yards, sweep under the ship, and as far as

the eye can reach, are seen advancing and passing away, as regularly as

the furrows in a field. Such waves are caused by the regularity of the

trade winds. The height of the waves is not the same in all seas. It

is greater where the basin is deeper in proportion to the surface, and

also as the water is fresher and yields easier to the impulses of the

wind.

The height of waves has been variously measured. Some observers have

claimed to see them over one hundred feet high, but from twenty to

fifty feet is about the average of observations on the Atlantic. The

breadth of a wave is calculated as fifteen times its height. Thus, a

wave four feet high is sixty feet broad. The inclination of the sides

of the waves varies however with the force of the wind, and with the

strength of the secondary vibrations in the water, which may interfere

with the primary ones. The speed of the waves is only apparent like

the motion in a length of cloth shaken up and down. Floating objects

do not change their relative positions, but slowly, except in rising

and falling with the wave. The real movement of the sea is that of a

drifting current, which is slowly formed under the action of the wind,

and this is not rapid, but slow. The astronomer Airey says that every

wave 100 feet wide, traversing a sea 164 fathoms in average depth, has

a velocity of nearly 2,100 feet a second, or about fifteen and one-half

miles an hour; a wave 674 feet, moving over a sea 1,640 fathoms deep,

travels more than 69 feet a second, or nearly fifty miles an hour, and

this last calculation may be taken as the average speed of storm waves

in great seas. As, therefore, we can calculate the velocity of waves

from their width and the known depth of the sea, we can calculate the

depth of the sea from the known size and velocity of the waves. By this

method the depth of the Pacific between Japan and California has been

calculated from the size and speed of an earthquake wave, which was set

in motion by an eruption in Japan. The accuracy of the calculation was

afterward established by actual soundings.

It was formerly supposed that the disturbance of the waves did not

penetrate the depth of the water, below four or six fathoms, but this

has been found, on further observation, erroneous. Sand and mud have

been brought up from a depth of a hundred fathoms below the surface,

and experiments have shown that waves have a vertical influence 350

times their height. Thus a wave a foot high influences the bottom at

a depth of 50 fathoms, and a billow of the ocean 33 feet high is felt

below at a distance of 1 3/4 miles. At these great depths the action of

the wave is perhaps imaginary, but to this reason we can ascribe the

heavy swells which are often so dangerous. A hidden rock, far below the

surface, arrests some moving wave and causes an eddy, which, rising to

the surface, produces the "ground swells" which suddenly rise in the

neighborhood of submarine banks and endanger ships. This cause also

explains the tide races, which, coming from the depths of the ocean,

advance suddenly upon the beaches, destroying all that opposes them.

It is this cause which makes the position of light-houses upon certain

reefs so dangerous. The Bell Rock house, on the Scottish coast, stands

112 feet above the rock, and yet it is often covered with the waves

and foam, even after the tempest has ceased to rage. Such light-houses

are often washed away; as that at Minot's Ledge, on the coast of

Massachusetts, has often been. In consequence the modern method of

building these structures differs from that formerly in use. The custom

was to build them of solid masonry, hoping to make them strong enough

to resist the waves. Now they are generally built of iron lattice open

work, making the bars as slender as is consistent with the proper

strength, so as to offer the least resisting surface to the rushing

water. This open frame work is raised up high enough, if possible, to

place the house and lantern above the reach of the body of the wave.

The force of the water in such positions is prodigious. Stephenson

calculated that the sea dashed against the Bell Rock light-house with

a force of 17 tons for every square yard. At breakwaters in exposed

situations the sea has been known to seize blocks of stone weighing

tons, and hurl them as a child would pebbles. At Cherbourg, in France,

the heaviest cannon have been displaced; and at Barra Head, in the

Hebrides, Stephenson states that a block of stone weighing 43 tons

was driven by the breakers about two yards. At Plymouth, England, a

vessel weighing 200 tons was thrown up on the top of the dike, and left

there uninjured. At Dunkirk it has been found that from the dash of

the breakers the ground trembles for more than a mile from the shore.

Results of this kind, to which our attention is specially directed,

since they affect man's work, show us what must be the effect produced

by the sea, in constantly eating away the shore; altering the coast

lines; changing continents, and building them up elsewhere; and suggest

how much greater than what we see must have been the effects of the sea

upon the land during the countless ages in which it has been at work.

The currents in the ocean, which constitute the real motion of its

waters, are very important in the study of the influence of the sea

upon the land. By these the circulation of the waters of the globe

is carried on. The warm water of the equatorial regions seeking the

poles, and a counter movement from the poles to the equator, is

established. By their means a constant mingling of the waters on the

face of the whole earth is maintained, and the wonderful similarity

of its different portions, in their composition, appearance, and the

substances held in solution, is produced. The chief causes of this

grand circulation are found in the heat of the sun and in the rotation

of the earth upon its axis. By the evaporation of the waters in the

tropics the surface of that portion of the ocean is estimated to be

lowered more than fourteen feet yearly. By this means not only is the

atmosphere provided with its store of vapor, to be dispensed in rain

upon the land, and thus returned again to the sea, but this lowering of

the surface of the ocean, in one part, leads to the currents flowing

from the others to restore the equilibrium. The same cause leading also

to the circulation of the atmosphere, produces the trade winds, which

aid in producing the currents in the ocean.

Now that by study and observation mankind have arrived at the

conception of the form of the earth, at its general features, and

can, in idea, grasp it as a whole, the opportunity is prepared for

the methodical study of its parts, and their relation to each other;

and this is the subject which for the first time in the history of

mankind is offered to the physical geographer, with the certainty that

none of his observations can be lost, but that they all are important,

and can each be referred to its proper place. Another movement of the

ocean is the tides. To the ancients, unacquainted with the form of the

earth, its position in space, or its relations with the other bodies of

the solar system, the tides were naturally inexplicable. It has been

possible, only in modern times to attempt their explanation. Kepler

first indicated the course to be followed; and Descartes and Newton

each gave a theory; the first that of the pressure of the waters; the

last, that of the attraction of the sun and moon upon the waters. This

last theory is the one generally accepted, since it has been found

satisfactory in most respects; yet it still has its opponents. Now,

however, that the telegraph has been discovered, and a means thus

afforded for instantaneous communication between observers at distant

points, it has become possible to organize a simultaneous observation

of the tides at various places, and eventually this will be done, so

that the theory that the tides are caused by the attraction of the sun

and moon will be entirely proved or rejected according as it will be

found consistent with the facts observed.

In this connection an interesting instance of the different manner

in which the ancients regarded natural phenomena, from that in which

the moderns regard the same occurrences, is found in the fear the

ancients had of the two monsters Scylla and Charybdis, which were the

fabled guardians of the Straits of Messina. At present there are no

straits in the Mediterranean more frequented than those of Messina.

By the soundings which have been made there, these monsters had been

effectually destroyed, and the whirlpools are known to be produced by

the ebb and flow of the tide, causing a greater flow of water than

can be accommodated by the narrow channel. The width of the channel

is hardly two miles, and at low tide it has often been crossed on

horseback, by swimming. The rising tide tends toward the north, from

the Ionian to the Tyrrhenian sea, and the falling tide in the opposite

direction. There is a strife between these currents, and on their

confines eddies are formed which ships avoid, but there is no danger

unless the wind blows strongly against the tide.

Besides the influence of the currents and the tides of the ocean

in altering the configuration of the land, the sea is the home of

innumerable forms of animal life, which are constantly laboring

in the same direction. It has been truly said, that a beef bone,

thrown overboard by a sailor on a ship, may form the nucleus of a new

continent. The entire chalk cliffs of England were formed from the

minute shells deposited by the small animals which secreted them. At

their death these fell to the bottom, and thus slowly through the ages

the deposit was formed. The recent deep sea dredgings have shown the

sea, at all depths, is full of animal life; and as the steady fall of

snow-flakes in a winter's storm, piled up by currents of wind, form the

drifts, or falling quietly, cover the ground uniformly, so the sea is

full of the minute shells, which, carried by currents, form banks, or,

falling evenly, prepare the plains which in the future will appear, in

some upheaval, to form new continents.

In the United States the peninsula of Florida is an evidence of the

land produced by the labor of the coral polyp. Florida has now ceased

to increase toward the east, for on this side it touches the deep

waters of the gulf, and the polyps can live only in shallow water. The

peninsula increases only on its southern and western coasts. The cut

at the end of this chapter represents the appearance of coral islands

as they first rise to the surface, before the gathering soil provides

the conditions for covering them with the luxuriant vegetation of the

tropics.

The cut at the head of this chapter, of an aquarium, represents a

new appliance of modern times, which is a most valuable aid in our

obtaining a knowledge of the habits of the animals living in the

sea. In fresh water, as well as in salt, the mutual relations of

the vegetable and animal life serve to keep the water from becoming

stagnant. The plants secrete the carbonic acid gas, which the animals

give to the water by breathing, and in so doing free the oxygen which

the animals require. In keeping therefore an aquarium, the desired

point is to provide such a natural proportion of vegetable and animal

life as shall preserve this balance. In many of the larger museums

of Europe, large aquariums have been built, and an opportunity thus

afforded for the study of the various animal forms, the habits of the

vegetable growths, and their relations. Some of these structures are

so arranged that they surround a room which receives its light only

through the water in the aquaria, and thus the spectator, without

disturbing the fish, can watch them feeding and performing all their

actions.

From this arrangement of the aquaria, as the light passes from the

water to the eye, the spectator is not disturbed in his vision, as

he is by trying to look into the water from above, by the refraction

of the light. A great deal that has been learned in modern times

concerning the growth of the vegetation of the sea, of the habits of

the animals, of their manner of life, their food and their growth, has

been obtained from the chance of observation afforded by the various

aquaria. Beside the positive benefits which have thus resulted from the

public aquaria, those in smaller form afford for the lover of natural

history a new and interesting way of carrying on his studies. In this

way also the habits of observation are formed in the young, and it is

fair to believe that the spirit of inquiry thus excited will tend to

increase the knowledge of the phenomena of life, and its relations to

the conditions of existence.

It has been by this course that the race itself has risen from

barbarism to its present degree of civilization, and with the new

appliances of modern times, it is evidently impossible to limit the

probabilities of advance in the future.

A few facts about the extent of our commerce will show the difference

of the spirit with which the ocean is regarded in modern times,

compared with that prevailing in antiquity; and the different use we

have learned to make of it, from the time when the exchanges of the

world were confined to a few coasters, who hardly ventured out of the

sight of land. To give even the most condensed summary of the world's

commerce to-day would require a series of volumes; but a few figures

taken from our own will enable the reader to judge of that which is

now going on all over the world, uniting the most distantly separated

nations; enabling them to become acquainted with each other; and

impressing them with the fact that by industry alone are the material

comforts of life to be attained, and that the task before humanity is

to become acquainted with the products of the world, with the forces of

which it is the theatre, and learn to control them for our own benefit.

From the report of the Bureau of Statistics, for a portion of 1873,

we learn that the imports and exports of the United States during

eight months, ending with February, 1873, amounted to the following

totals: Imported in American vessels, $104,891,248; imported in foreign

vessels, $317,043,490; imported in land vehicles, $12,356,325. During

the same period the domestic exports in American vessels amounted to a

total of $108,246,698; in foreign vessels, $311,816,048; and in land

vehicles, $5,282,949. At the same time the re-exportation of foreign

products amounted in American vessels to $5,147,805; in foreign vessels

to $10,938,300; and in land vehicles to $1,693,795.

The number and tonnage of American and foreign vessels engaged in the

foreign trade, which entered and cleared during the twelve months

ending with February, 1873, was as follows: American vessels, 10,928,

carrying 3,597,474 tons; foreign vessels, 19,220, carrying 7,622,416

tons. The report of the Bureau for 1872, gives the following totals

of the number of vessels and their tonnage engaged in the commerce of

the United States. Upon the Atlantic and Gulf coasts, 21,940 vessels

carrying 2,916,001,058 tons. On the Western rivers, 1,476 vessels

carrying 354,938,052 tons. On the Northern lakes 5,339 vessels,

carrying 726,105,051 tons. On the Pacific coast, 1,094 vessels carrying

161,987,050.

From the port of New York alone there are now thirteen lines of

steamships plying to Europe. Of these the Anchor line has 15 steamers,

with a tonnage of 36,127 tons; the Baltic Lloyds has 4 vessels of 9,200

tons; the Cardiff (a Welsh) line has three vessels of 8,000 tons; the

Cunard has 23 vessels of 59,308 tons; the Holland (direct) line has two

vessels of 4,000 tons; the General Transatlantic (a French line) has 5

vessels of 17,000 tons; the Hamburg has 15 vessels of 45,000 tons; the

Inman line has 12 vessels of 34,811; the Liverpool and Great Western

line has 7 vessels of 23,573 tons; the North German line has 20 vessels

of 60,000 tons; the National line has 12 vessels of 50,062 tons; the

State line has 3 vessels of 7,500 tons; and the White Star line has 6

vessels of 23,064 tons. Beside these ships, the thirteen companies are

building from 30 to 40 more steamers to meet the demand for freight.

The ocean has thus become almost a steam ferry; almost every day a

steamer leaves for Europe. With this knowledge of how far we have

progressed in becoming acquainted with the ocean, it will be well to

consider for a moment how much still remains for us to explore. In

the middle ages, and even down to modern times, the maps of the world

represented all unknown lands as inhabited by monsters; but every

voyage made by discoverers has contracted the limits of these fables,

until they have finally about disappeared. Still at the North Pole and

in the Antarctic regions areas extending over a space of 2,900,000

and 8,700,000 square miles, respectively, have been, up to this time,

unvisited. The icebergs and mountains of ice have kept them from our

accurate investigations. The difficulties of such a sea are well shown

in the adjoining illustration.

Discoveries have also to be made in the interiors of Africa, Asia,

South America and Australia before the civilized portions of the

race can claim a complete knowledge of the earth, their common

dwelling-place. Every year, however, the portions unexplored grow

smaller and smaller, so that we are justified in believing that

eventually the whole world will be known to us, from actual observation.

[Illustration: APPEARANCE OF ICE.]

[Illustration: LIGHT SHIP AND INCOMING VESSEL.]

Another difference which our extended knowledge of the world has

produced is this: The mariner now approaching an unknown coast does

not fear to meet monsters, but looks out for the light-house, the

light-ships, the buoys, and other evidences of civilization, by which

the dangers of the coast are pointed out to the voyager. As a contrast

with some of the pictures already given, representing the approach to

the land of the early explorers, the illustration of the light-ship

will show how differently to-day a voyage approaches its termination.

Instead of looking out for enemies, and preparing weapons for use, a

package of newspapers and letters is got ready, and the news boat,

which lies ready at hand, is prompt to seize them, and hasten with

these to spread the news of another safe arrival. It is thus that

science, which is gradually preparing the means for converting the

globe into one great organism for the benefit of mankind, points out

the way for making it the abode of that harmony, peace and plenty which

has been dreamed of by the poets of all time. For this it is only

necessary that our moral progress should keep pace with our advance in

knowledge. The globe will never become the abode of perfect harmony

until men are united in a universal league of justice and peace. And in

aiding toward the production of this most desirable consummation, what

has been here written will show how important has been the part taken

by the ocean.

[Illustration: A CORAL ISLAND.]

FOOTNOTES:

[1] A late French biography of Columbus, a work of profound research

and erudition, by M. Roselly de Lorgues, proves beyond a cavil the

accuracy of this assertion. The work in question was published under

the auspices of the Pope.

[2] This tract, so thickly matted with Gulf-weed, and covering an area

equal in extent to the Mississippi Valley, has since been called by the

Portuguese the Sargasso Sea. It still exists in the same spot, and if

we now hear very little of it, it is because navigators have learned

to avoid it. Lieut. Maury accounts for its existence in the following

manner:--"Patches of this weed are always to be seen floating along the

Gulf Stream. Now, if bits of cork, or chaff, or any floating substance,

be put in a basin, and a circular motion be given to the water, all

the light substances will be found crowding together near the centre

of the pool, where there is the least motion. Just such a basin is the

Atlantic Ocean to the Gulf Stream, and the Sargasso Sea is the centre

of the whirl. Columbus found this weedy sea in his voyage of discovery,

and there it has remained to this day."

[3] Mr. John Mullaly.

TRANSCRIBER'S NOTE

-Obvious print and punctuation errors fixed.