The first divers learned their art by early and adventurous experience,
in trying to continue under water as long as possible without
breathing; and, indeed, it must be allowed that some of them carried it
to very great perfection. This art, however, excites little surprise;
for, like running, throwing, and other bodily dexterities, it requires
only practice; but it is certain that those nations called by us
uncultivated and savage excel in it the Europeans[274], who, through
refinement and luxury, have become more delicate, and less fit for such
laborious exercises.
In remote ages, divers were kept in ships to assist in raising
anchors[275], and goods thrown overboard in times of danger[276]; and,
by the laws of the Rhodians, they were allowed a share of the wreck,
proportioned to the depth to which they had gone in search of it[277].
In war, they were often employed to destroy the works and ships of the
enemy. When Alexander was besieging Tyre, divers swam off from the
city, under water, to a great distance, and with long hooks tore to
pieces the mole with which the besiegers were endeavouring to block up
the harbour[278]. The pearls of the Greek and Roman ladies were fished
up by divers at the great hazard of their lives; and by the like means
are procured at present those which are purchased as ornaments by our
fair.
I do not know whether observations have ever been collected respecting
the time that divers can continue under water. Anatomists once believed
that persons in whom the oval opening of the heart (_foramen ovale_)
was not closed up, could live longer than others without breathing, and
could therefore be expert divers. Haller[279], however, and others,
have controverted this opinion; as people who had that opening have
been soon suffocated, and as animals which have it not can live a long
time under water: besides, when that opening is perceptible in grown
persons, it is so small as not to be sufficient for that purpose,
especially as the _ductus arteriosus_ is scarcely ever found open.
The divers of Astracan, employed in the fishery there, can remain only
seven minutes under water[280]. The divers in Holland seem to have
been more expert. An observer, during the time they were under water,
was obliged to breathe at least ten times[281]. Those who collect
pearl-shells in the East Indies can remain under water a quarter of
an hour, though some are of opinion that it is possible to continue
longer; and Mersenne mentions a diver, named John Barrinus, who could
dive under water for six hours[282]. How far this may be true I shall
leave others to judge.
[The various statements regarding the length of time during which
divers can remain under water, unaided by apparatus for renewing the
supply of atmospheric air, are not borne out by the experience of those
who have carefully observed and noted these phænomena. The average time
which human beings can remain in the water under these conditions, is
one and a half or two minutes[283]; extraordinary cases are attested
where five and even six minutes have elapsed, but these are exceedingly
rare instances and far beyond the average; no instance of a longer
time than this is recorded on credible authority. Some interesting
remarks on this point were made not long since by a member of the
Asiatic Society to Dr. Faraday. The lungs in their natural state are
charged with a large quantity of impure air; this being a portion of
the carbonic acid gas which is formed during respiration, but which,
after each expiration, remains lodged in the involved passages of the
pulmonary tubes. By breathing hard for a short time, as a person does
after violent exercise, this impure air is expelled, and its place is
supplied by pure atmospheric air, by which a person will be enabled to
hold his breath much longer than without such precaution. Dr. Faraday
states, that although he could only hold his breath, after breathing in
the ordinary way, for about three-fourths of a minute, and that with
great difficulty, he felt no inconvenience, after making eight or ten
forced respirations to clear the lungs, until the mouth and nostrils
had been closed more than a minute and a half; and that he continued
to hold breath to the end of the second minute. A knowledge of this
fact may enable a diver to remain under water at least twice as long as
he otherwise could do. It is suggested that possibly the exertion of
swimming may have the effect of occasioning the lungs to be cleared, so
that persons accustomed to diving may unconsciously avail themselves of
this preparatory measure.]
It is certain, however, that men began very early to contrive means
for supplying divers with air under the water, and of thereby enabling
them to remain under it much longer. For this purpose the diving-bell,
_campana urinatoria_, was invented. Those who had no idea of this
machine, might have easily been led to it by the following experiment.
If a drinking-glass inverted be immersed in water, in such a manner
that the surface of the water may rise equally around the edge of the
glass, it will be found that the glass does not become filled with
water, even when pressed down to the greatest depth; for where there
is air no other body can enter, and by the above precaution the air
cannot be expelled by the water. In like manner, if a bell of metal be
constructed under which the diver can stand on a stool suspended from
it so that the edge of the bell may reach to about his knee, the upper
part of his body will be secured from water, and he can, even at the
bottom of the sea, breathe the air enclosed in the bell.
The invention of this bell is generally assigned to the sixteenth
century, and I am of opinion that it was little known before that
period. We read, however, that even in the time of Aristotle divers
used a kind of kettle to enable them to continue longer under water;
but the manner in which it was employed is not clearly described.
The oldest information we have respecting the use of the diving-bell
in Europe is that of John Taisnier, quoted by Schott[284]. The former,
who was born at Hainault in 1509, had a place at court under Charles
V., whom he attended on his voyage to Africa. He relates in what manner
he saw at Toledo, in the presence of the emperor and several thousand
spectators, two Greeks let themselves down under water, in a large
inverted kettle, with a burning light, and rise up again without being
wet. It appears that this art was then new to the emperor and the
Spaniards, and that the Greeks were induced to make the experiment in
order to prove the possibility of it. After this period the use of the
diving-bell seems to have become still better known. It is described
more than once in the works of Lord Bacon, who explains its effects,
and remarks that it was invented to facilitate labour under the
water[285].
In the latter part of the seventeenth century the diving-bell was
sometimes employed in great undertakings. When the English, in the year
1588, dispersed the Spanish fleet called the Invincible Armada, part
of the ships went to the bottom near the Isle of Mull, on the western
coast of Scotland; and some of these, according to the account of the
Spanish prisoners, contained great riches. This information excited,
from time to time, the avarice of speculators, and gave rise to several
attempts to procure part of the lost treasure. In the year 1665, a
person was so fortunate as to bring up some cannon, which, however,
were not sufficient to defray the expenses. Of these attempts, and
the kind of diving-bell used, an account has been given by a Scotsman
named Sinclair[286]; but Paschius[287], Leupold[288] and others falsely
ascribe the invention of this machine to that learned man. He himself
does not lay claim to this honour; but says only, that he conversed
with the artist and measured the machine.
Some years after attempts of the like kind were renewed. William
Phipps, the son of a blacksmith, born in America in 1650, and who
had been brought up as a ship-carpenter at Boston, formed a project
for searching and unloading a rich Spanish ship sunk on the coast of
Hispaniola, and represented his plan in such a plausible manner,
that king Charles II. gave him a ship, and furnished him with every
thing necessary for the undertaking. He set sail in the year 1683;
but, being unsuccessful, returned again in great poverty, though with
a firm conviction of the possibility of his scheme. He endeavoured,
therefore, to procure another vessel from James II., who was then on
the throne; but as he failed in this, he tried to find the means of
executing his design by the support of private persons, and, according
to the prevailing practice, opened for that purpose a subscription.
At first he was laughed at; but at length the duke of Albemarle,
son of the celebrated General Monk, took part in it, and advanced a
considerable sum to enable him to make the necessary preparations for
a new voyage. Phipps soon collected the remainder; and in 1687 set
sail in a ship of two hundred tons burthen to try his fortune once
more, having previously engaged to divide the profit according to the
twenty shares of which the subscription consisted. At first, all his
labour proved fruitless; but at last, when his patience was almost
entirely exhausted, he was so lucky as to bring up, from the depth of
six or seven fathoms, so much treasure, that he returned to England
with the value of two hundred thousand pounds sterling. Of this sum he
himself got about sixteen, others say twenty thousand, and the duke
ninety thousand pounds. After he came back, some persons endeavoured
to persuade the king to seize both the ship and the cargo, under a
pretence that Phipps, when he solicited for his Majesty’s permission,
had not given accurate information respecting the business. But the
king answered, with much greatness of mind, that he knew Phipps to be
an honest man, and that he and his friends should share the whole among
them, had he returned with double the value. His Majesty even conferred
upon him the honour of knighthood, to show how much he was satisfied
with his conduct. This Phipps was afterwards high sheriff of New
England, and died at London, greatly respected, in 1693. This affair
was attended with such good consequences to the duke of Albemarle, that
he obtained from the king the governorship of Jamaica, in order to try
his fortune with other ships sunk in that neighbourhood. But whether it
was that the gold had been already taken from the one before-mentioned,
or that, when the vessel went to pieces, the sea had dispersed the
cargo, it is certain that nothing further was found worth the labour of
searching for[289].
In England, however, several companies were formed, and obtained
exclusive privileges of fishing up goods on certain coasts, by means
of divers. The most considerable of these was that which, in 1688,
tried its success at the Isle of Mull, and at the head of which was
the earl of Argyle. The divers went down to the depth of sixty feet
under water, remained there sometimes a whole hour, and brought up gold
chains, money, and other articles, which, however, when collected,
were of very little importance[290]. Without giving more examples of
the use of the diving-bell, I shall now mention some of those who,
in later times, have endeavoured to improve it. That this machine
was very little known in the first half of the sixteenth century,
I conclude from the following circumstance. To the oldest edition
of Vegetius on the art of war, there are added, by the editor, some
figures, of which no explanation is given in the book. Among these is
represented a method of catching fish with the hands, at the bottom of
the sea. The apparatus for this purpose consists of a cap, which is
fitted so closely to the head of the diver that no water can make its
way between; and from the cap there ascends a long leather pipe, the
opening of which floats on the surface of the water. Had the person
who drew these figures been acquainted with the diving-bell, he would
certainly have delineated it rather than this useless apparatus[291].
Of the old figures of a diving machine, that which approaches nearest
to the diving-bell is in a book on fortification, by Lorini; who
describes a square box bound round with iron, which is furnished with
windows, and has a stool affixed to it for the diver. This more
ingenious contrivance appears, however, to be older than that Italian;
at least he does not pretend to be the inventor of it[292].
In the year 1617, Francis Kessler gave a description of his
water-armour[293], intended also for diving, but which cannot really
be used for that purpose[294]. In the year 1671, Witsen taught, in a
better manner than any of his predecessors, the construction and use of
the diving-bell[295]; but he is much mistaken when he says that it was
invented at Amsterdam. In 1679 appeared, for the first time, Borelli’s
well-known work De Motu Animalium[296], in which he not only described
the diving-bell, but also proposed another, the impracticability of
which was shown by James Bernoulli[297]. When Sturm published his
Collegium Curiosum, in 1678, he proposed some hints for the improvement
of this machine, on which remarks were made in the Journal des Sçavans
(Jan. 1678). None, however, have carried their researches further for
this purpose than Dr. Halley, and Triewald, a Swede.
The bell which Edmund Halley, secretary to the Royal Society, caused
to be made, was three feet broad at the top, five feet at the bottom,
and eight feet in height; forming a cavity of sixty-three cubic
feet. It was covered with lead; and was so heavy that it sunk to the
bottom, even when entirely empty. Around the lower edge, weights were
disposed in such a manner that it should always sink in a perpendicular
direction, and never remain in an oblique position. In the top was
fixed a piece of strong glass to admit the light from above, and
likewise a valve to give a passage to the air corrupted by the breath.
Around the whole circumference of the bottom was placed a seat, on
which the divers sat; and a stool, fixed to ropes, hung below, on which
they could stand in order to work. The whole machine was suspended
from a cross beam fastened to the mast of a ship, so that it could
be easily lowered down into the water and again drawn up. That the
bell might be supplied with fresh air under the water, large vessels
filled with air, and which had an opening below through which the water
compressed the included air, were let down by ropes. In the top of
these vessels were leather pipes, besmeared with oil, through which the
diver introduced air from the vessels into the bell; and as soon as a
vessel was emptied, it was drawn up, on a signal made by the diver,
and another let down. The foul air in the bell, being the warmest and
lightest, rose to the top of the machine, where it was suffered to
escape through the valve before-mentioned. By these means the bell
could be continually supplied with fresh air in such abundance, that
Halley, and four other persons, remained under water, at the depth of
ten fathoms, an hour and a half, without suffering the least injury,
and could, with equal security, have continued longer, or even as long
as they might have wished. This precaution, however, is necessary,
that the bell be let down at first very slowly, that the divers may be
gradually accustomed to inspire the compressed air; and at every twelve
fathoms the bell must be held fast, in order to expel the water which
has rushed in, by letting fresh air into it. By such apparatus, Halley
was enabled to make the bottom of the sea, within the circumference
of the bell, so dry that the sand or mud did not rise above his shoe.
Through the window, in the top, so much light was admitted, that when
the sea was still and the waves did not roll, he could see perfectly
well to read and write under the water. When the empty air-vessels were
drawn up, he sent up with them his orders, written with an iron spike
on a plate of lead, and could thus let those above know when he wished
to be removed with the bell to another place. In bad weather, and when
the sea was rough, it was as dark under the bell as at night; he then
kindled a light; but a burning candle consumed as much air as a man.
The only inconvenience of which Halley complained was, that, in going
down, he felt a pain in his ears, as if a sharp quill had been thrust
into them. This pain returned every time the bell was let down to a
greater depth, but soon went off again. A diver thought to prevent this
pain by putting chewed paper into both his ears; but the bits of paper
were forced in so far by the air, that a surgeon found great difficulty
to extract them.
Another improvement of the diving-bell was effected by the well-known
Triewald, a Swede, in 1732. His bell, which was much smaller and more
commodious, was made of copper, tinned in the inside. On the top there
were panes of glass, which, for the greater security, were fixed in a
frame of the same metal. The stool below was placed in such a manner,
that the head only of the diver, when he stood upon it, rose above the
surface of the water in the bell. This situation is much better than
when the whole body is raised above the water in the bell, because near
the surface of the water the air is much cooler and fitter to breathe
in than at the top of the machine. That the diver also might remain
conveniently in the upper part of the bell, Triewald arranged his
apparatus so that when the diver had breathed as long as possible in
the upper air, he found at the side of the bell a spiral pipe, through
which he could draw in the lower cool air which was over the surface of
the water. To the upper end of this copper pipe was affixed a pliable
leather one, with an ivory mouth-piece, which the diver put into his
mouth, and could thus inspire fresh air, in whatever position his body
might be[298].
[In 1776, Mr. Spalding of Edinburgh made some improvements in Dr.
Halley’s diving-bell, for which he was rewarded by the Society of
Arts. His diving-bell was made of wood, and was so light, that, with
the divers and the weights attached to its rim, it would not sink;
the weight necessary to counteract its buoyancy being added in the
form of a large balance-weight, suspended from its centre by a rope,
which was so mounted on pulleys that the divers could either draw
the balance-weight up to the mouth of the bell or allow it to fall a
considerable depth below it. Thus by letting the weight down to the
bottom, the divers could, as it were, anchor the bell at any required
level, or prevent its further descent if they perceived a rock or part
of a wreck beneath it, which might otherwise overturn it. Also, by
hauling in the rope while the weight was at the bottom, the persons
in the bell might lower themselves at pleasure. Another improvement
consisted in the addition of a horizontal partition near the top of the
bell, which divided off a chamber, that might, by suitable openings
and valves, be filled either with water or with air from the lower
part of the bell, so as to alter the specific gravity of the whole
machine, and thereby cause it to ascend or descend at pleasure. The
bell was supplied with air by an apparatus resembling that of Dr.
Halley, and ropes stretched across the bell were used instead of seats
and platforms for standing on. Thus the persons in the diving-bell
were enabled, in case of accident, to raise themselves to the surface
without any assistance from above, and it was rendered so perfectly
manageable, that it might be removed to a considerable distance from
the point at which it descended; its outward motion and its return to
the vessel for the purpose of being hauled up, being assisted by a long
boat, which carried the signal lines and the tackle for working the
air-barrels.
Mr. John Farey, junior, made an improvement in Spalding’s
apparatus[299]. The upper chamber of the diving-bell is very strong and
air-tight, without any openings for the admission of water. Two pumps
are fixed in the partition, by which air may be forced into the upper
chamber, whenever, during a pause in the descent, the lower chamber
or the cavity of the bell is replenished with air. By this means, the
upper chamber is made a reservoir of condensed air, from which the
bell may be replenished with air, when it is desired to increase its
buoyancy, by forcing out the water from the lower part. Hence also, the
buoyancy of the bell may be at any time diminished, by pumping some
of the air from it into the upper chamber, whereby the water will be
allowed to enter to a greater height; and as this is effected without
wasting the air, there is no danger of diminishing the buoyancy of the
machine to a degree which would prevent it from rising, in case the
suspending rope or chain should break.
Smeaton first employed the diving-bell in civil engineering operations
in repairing the foundations of Hexham bridge in 1779. The bell was
made of wood, and was supplied with air by means of a forcing-pump,
which was fixed to the top, and threw in a gallon of air at a time;
the river being shallow, the top of the bell was not covered with
water[300]. In 1788 he used a cast-iron one in repairing Ramsgate
harbour; a forcing-pump in a boat supplied air through a flexible tube.
Since that time it has been frequently used by Rennie and others in
submarine operations, recovering property from wrecks, blasting, &c.
Mr. Rennie has moreover constructed apparatus for moving the bell in
any direction.
In addition to the various forms of diving-bell, different water- and
air-tight dresses have been invented to enable divers to remain in
the water and perform various operations. Thus, Dr. Halley invented
a leaden cap which covered the diver’s head; it had glass before it,
and contained as much air as was sufficient for two minutes, and had
affixed to it a thick pliable pipe, with the other end fastened to the
bell, and which, at the cap, was furnished with a valve to convey fresh
air to the diver from the bell. This pipe, which the diver was obliged
to wind round his arm, served him also as a guide to find his way back
to the bell[301].
Mr. Martin states that a gentleman at Newton-Bushel, in Devonshire,
invented an apparatus consisting of a large case of strong leather,
holding about half a hogshead of air, made perfectly water-tight, and
adapted to the legs and arms, with a glass in the anterior part, so
that when the case was put on, he could walk about very easily at the
bottom of the sea, and go into the cabin and other parts of a ship in a
wreck, and deliver out the goods; and that he practised this method for
forty years, and thereby acquired a large fortune and equal fame[302].
M. Klingert also invented a similar kind of apparatus, and described
it in a pamphlet published at Breslau in 1798. The armour was made of
tin-plate, in the form of a cylinder, with a round end to enclose the
head and body; also, a leather jacket with short sleeves, and a pair of
water-tight drawers of the same, buttoned on the metal part, where they
joined, and were made tight by brass hoops. Two distinct flexible pipes
terminated in the helmet, and rose to the surface of the water; one was
for inhaling, and terminated in an ivory mouth-piece, the other was for
the escape of foul air. The body was kept down by weights.
Another method of supplying air to the apparatus was used by Mr. Tonkin
in 1804. This consisted in the application of a bellows or pump, until
the elastic force of the air was equal to the pressure of the water,
the foul air being allowed to escape into the water through a valve, or
conducted to the surface by a pipe[303].]