Chapter XI: David Bushnell

The originator of the modern method of submarine warfare was David Bushnell, a native of Saybrook (now Westbrook) in the State of Maine, U.S.A., who in the latter part of the eighteenth century conceived the idea of destroying the British ships of war which were employed upon the coasts of North America by exploding gunpowder, contained in a magazine, beneath their bottoms. In order the better to fix the charge to the ships, Bushnell built in 1775 the first practical submarine boat, and the first of which any detailed account is extant.

In a letter written in October, 1789, to Thomas Jefferson, the Minister Plenipotentiary of the United States at Paris, David Bushnell gives a very interesting description of his vessel and its achievements. This deserves to be printed here in full in view of the many quite remarkable devices (considering the period) which the inventor originated.

The external shape of the submarine vessel bore some resemblance to
two upper tortoise shells of equal size, joined together, the place
of entrance into the vessel being represented by the opening made by
the swell of the shells at the head of the animal. The inside was
capable of containing the operator and air sufficient to support him
thirty minutes without receiving fresh air. At the bottom, opposite
to the entrance, was fixed a quantity of lead for ballast. At one
edge, which was directly before the operator, who sat upright, was
an oar for rowing forward or backward. At the other edge was a
rudder for steering. An aperture at the bottom, with its valve, was
designed to admit water for the purpose of defending, and two brass
forcing pumps served to eject the water within when necessary for
ascending. At the top there was likewise an oar for ascending or
descending, or continuing at any particular depth. A water-gauge or
barometer determined the depth of descent, a compass directed the
course, and a ventilator within supplied the vessel with fresh air
when on the surface.

The entrance into the vessel was elliptical, and so small as barely
to admit a person. This entrance was surrounded with a broad
elliptical iron band, the lower edge of which was let into the wood,
of which the body of the vessel was made, in such a manner as to
give its utmost support to the body of the vessel against the
pressure of the water. Above the upper edge of this iron band there
was a brass crown or cover, resembling a hat with its crown and
brim, which shut watertight upon the iron band; the crown was hung
to the iron band with hinges so as to turn over sidewise when
opened. To make it perfectly secure when shut it might be screwed
down upon the band by the operator or by a person without.

There were in the brass crown three round doors, one directly in
front and one on each side, large enough to put the hand through.
When open they admitted fresh air. Their shutters were ground
perfectly tight into their places with emery, hung with hinges, and
secured in their places when shut. There were likewise several small
glass windows in the crown for looking through, and for admitting
light in the day-time, with covers to secure them. There were two
air-pipes in the crown. A ventilator within drew fresh air through
one of the air-pipes and discharged it into the lower part of the
vessel; the fresh air introduced by the ventilator expelled the
impure light air through the other air-pipe. Both air-pipes were so
constructed that they shut themselves whenever the water rose near
their tops, so that no water could enter through them, and opened
themselves immediately after they rose above the water.

The vessel was chiefly ballasted with lead fixed to its bottom; when
this was not sufficient a quantity was placed within, more or less
according to the weight of the operator; its ballast made it so
stiff that there was no danger of over-setting. The vessel, with all
its appendages and the operator, was of sufficient weight to settle
it very low in the water. About 200 lbs. of lead at the bottom for
ballast could be let down 40 or 50 feet below the vessel; this
enabled the operator to rise instantly to the surface of the water
in case of accident.

When the operator would descend he placed his foot upon the top of a
brass valve, depressing it, by which he opened a large aperture in
the bottom of the vessel, through which the water entered at his
pleasure; when he had admitted a sufficient quantity he descended
very gradually; if he admitted too much he ejected as much as was
necessary to obtain an equilibrium by the two brass forcing pumps
which were placed at each hand. Whenever the vessel leaked or he
would ascend to the surface he also made use of these forcing pumps.
When the skilful operator had obtained an equilibrium he could row
upward or downward, or continue at any particular depth, with an oar
placed near the top of the vessel, formed upon the principle of the
screw, the axis of the oar entering the vessel; by turning the oar
one way he raised the vessel, by turning it the other way he
depressed it.

A glass tube 18 inches long and 1 inch in diameter, standing
upright, its upper end closed, and its lower end, which was open,
screwed into a brass pipe, through which the external water had a
passage into the glass tube, served as a water-gauge or barometer.
There was a piece of cork with phosphorus on it put into the
water-gauge. When the vessel descended the water rose into the
water-gauge, condensing the air within, and bearing the cork with
its phosphorus on its surface. By the light of the phosphorus the
ascent of the water in the gauge was rendered visible, and the depth
of the vessel under water ascertained by a graduated line.

An oar, formed upon the principle of the screw, was fixed in the
forepart of the vessel; its axis entered the vessel, and being
turned one way, rowed the vessel forward, but being turned the other
way rowed it backward; it was made to be turned by the hand or foot.

A rudder, hung to the hinder part of the vessel, commanded it with
the greatest ease. The rudder was made very elastic, and might be
used for rowing forward. Its tiller was within the vessel, at the
operator’s right hand, fixed at a right angle on an iron rod which
passed through the side of the vessel; the rod had a crank on its
outside end which commanded the rudder by means of a rod extending
from the end of the crank to a kind of tiller fixed upon the left
hand of the rudder. Raising and depressing the first-mentioned
tiller turned the rudder as the same required. A compass marked with
phosphorus directed the course, both above and under the water, and
a line and lead founded the depth when necessary.

The internal shape of the vessel, in every possible section of it,
verged towards an ellipsis, as near as the design would allow, but
every horizontal section, although elliptical, yet as near to a
circle as could be admitted. The body of the vessel was made
exceedingly strong, and to strengthen it as much as possible a firm
piece of wood was framed, parallel to the conjugate diameter, to
prevent the sides from yielding to the great pressure of the
incumbent water in a deep immersion. This piece of wood was also a
seat for the operator.

Every opening was well secured. The pumps had two sets of valves.
The aperture at the bottom for admitting water was covered with a
plate perforated full of holes to receive the water and prevent
anything from choking the passage or stopping the valve from
shutting. The brass valve might likewise be forced into its place
with a screw if necessary. The air-pipes had a kind of hollow sphere
fixed round the top of each to secure the air-pipe valves from
injury; these hollow spheres were perforated full of holes for the
passage of the air through the pipes. Within the air-pipes were
shutters to secure them should any accident happen to the pipes or
the valves on their tops.

BUSHNELL’S SUBMARINE
]

Wherever the external apparatus passed through the body of the
vessel the joints were round and formed by brass pipes, which were
driven into the wood of the vessel, the holes through the pipes were
very exactly made, and the iron rods which passed through them were
turned in a lathe to fit them; the joints were also kept full of oil
to prevent rust and leaking. Particular attention was given to bring
every part necessary for performing the operations, both within and
without the vessel, before the operator, and as conveniently as
could be devised, so that everything might be found in the dark
except the water-gauge and the compass, which were visible by the
light of the phosphorus, and nothing required the operator to turn
to the right hand or to the left to perform anything necessary.

_Description of a Magazine and its Appendages designed to be conveyed
by the Submarine Vessel to the bottom of a Ship._

In the forepart of the brim of the crown of the submarine vessel was
a socket, and an iron tube passing through the socket; the tube
stood upright, and could slide up and down in the socket 6 inches.
At the top of the tube was a wood screw (A), fixed by means of a
rod, which passed through the tube, and screwed the wood screw fast
upon the top of the tube; by pushing the wood screw up against the
bottom of the ship and turning it at the same time it would enter
the planks; driving would also answer the same purpose. When the
wood screw was firmly fixed it could be cast off by unscrewing the
rod, which fastened it upon the top of the tube.

Behind the submarine vessel was a place above the rudder for
carrying a large powder magazine. This was made of two pieces of oak
timber, large enough when hollowed out to contain 150 lbs. of
powder, with the apparatus used in firing it, and was secured in its
place by a screw turned by the operator. A strong piece of rope
extended from the magazine to the wood screw (A) above mentioned,
and was fastened to both. When the wood screw was fixed, and to be
cast off from its tube, the magazine was to be cast off likewise by
unscrewing it, leaving it hanging to the wood screw; it was lighter
than the water, that it might rise up against the object to which
the wood screw and itself were fastened.

Within the magazine was an apparatus constructed to run any proposed
length of time under twelve hours; when it had run out its time it
unpinioned a strong lock resembling a gunlock, which gave fire to
the powder. This apparatus was so pinioned that it could not
possibly move till, by casting off the magazine from the vessel, it
was set in motion.

The skilful operator could swim so low on the surface of the water
as to approach very near a ship in the night without fear of being
discovered, and might, if he chose, approach the stem or stern above
water with very little danger. He could sink very quickly, keep at
any depth he pleased, and row a great distance in any direction he
desired without coming to the surface, and when he rose to the
surface he could soon obtain a fresh supply of air. If necessary he
might descend again and pursue his course.

_Experiments made to prove the nature and use of a Submarine Vessel._

The first experiment I made was with about two ounces of gunpowder,
which I exploded 4 feet under water, to prove to some of the first
personages in Connecticut that powder would take fire under water.

The second experiment was made with 2 lbs. of powder enclosed in a
wooden bottle and fixed under a hogshead, with a 2–inch oak plank
between the hogshead and the powder. The hogshead was loaded with
stones as deep as it could swim; a wooden pipe descending through
the lower head of the hogshead and through the plank into the powder
contained in the bottle, was primed with powder. A match put to the
priming exploded the powder, which produced a very great effect,
rending the plank into pieces, demolishing the hogshead, and casting
the stones and the ruins of the hogshead, with a body of water, many
feet into the air, to the astonishment of the spectators. This
experiment was likewise made for the satisfaction of the gentlemen
above mentioned.

I afterwards made many experiments of a similar nature, some of them
with large quantities of powder; they produced very violent
explosions, much more than sufficient for any purpose I had in view.

In the first essays with the submarine vessel I took care to prove
its strength to sustain the great pressure of the incumbent water
when sunk deep before I trusted any person to descend much below the
surface, and I never suffered any person to go under water without
having a strong piece of rigging made fast to it, until I found him
well acquainted with the operations necessary for his safety. After
that I made him descend and continue at particular depths, without
rising or sinking, row by the compass, approach a vessel, go under
her, and fix the wood screw mentioned in No. 2, and marked A, into
her bottom, &c., until I thought him sufficiently expert to put my
design into execution.

I found, agreeably to my expectations, that it required many trials
to make a person of common ingenuity a skilful operator. The first I
employed was very ingenious, and made himself master of the
business, but was taken sick in the campaign of 1776 at New York
before he had an opportunity to make use of his skill, and never
recovered his health sufficiently afterwards.

After various attempts to find an operator to my wish, I sent one
who appeared more expert than the rest from New York to a 50–gun
ship lying not far from Governor’s Island. He went under the ship
and attempted to fix the wooden screw into her bottom, but struck,
as he supposes, a bar of iron which passes from the rudder hinge,
and is spiked under the ship’s quarter. Had he moved a few inches,
which he might have done without rowing, I have no doubt but he
would have found wood where he might have fixed the screw, or if the
ship were sheathed with copper he might easily have pierced it; but
not being well skilled in the management of the vessel, in
attempting to move to another place he lost the ship. After seeking
her in vain for some time, he rowed some distance and rose to the
surface of the water, but found daylight had advanced so far that he
durst not renew the attempt. He says that he could easily have
fastened the magazine under the stem of the ship above water, as he
rowed up to the stern and touched it before he descended. Had he
fastened it there the explosion of 150 lbs. of powder (the quantity
contained in the magazine) must have been fatal to the ship. In his
return from the ship to New York he passed near Governor’s Island,
and thought he was discovered by the enemy on the island. Being in
haste to avoid the danger he feared, he cast off the magazine, as he
imagined it retarded him in the swell, which was very considerable.
After the magazine had been cast off one hour, the time the internal
apparatus was set to run, it blew up with great violence.

Afterwards there were two attempts made in Hudson’s River, above the
city, but they effected nothing. One of them was by the
afore-mentioned person. In going towards the ship he lost sight of
her, and went a great distance beyond her. When he at length found
her the tide ran so strong that, as he descended under water for the
ship’s bottom, it swept him away. Soon after this the enemy went up
the river and pursued the boat which had the submarine vessel on
board, and sunk it with their shot. Though I afterwards recovered
the vessel, I found it impossible at that time to prosecute the
design any farther. I had been in a bad state of health from the
beginning of my undertaking, and was now very unwell; the situation
of public affairs was such that I despaired of obtaining the public
attention and the assistance necessary. I was unable to support
myself and the persons I must have employed had I proceeded.
Besides, I found it absolutely necessary that the operators should
acquire more skill in the management of the vessel before I could
expect success, which would have taken up some time, and made no
small additional expense. I therefore gave over the pursuit for that
time, and waited for a more favourable opportunity, which never
arrived.

In the year 1777 I made an attempt from a whale-boat against the
_Cerberus_ frigate, then lying at anchor between Connecticut River
and New London, by drawing a machine against her side by means of a
line. The machine was loaded with powder, to be exploded by a
gunlock, which was to be unpinioned by an apparatus to be turned by
being brought alongside of the frigate. This machine fell in with a
schooner at anchor astern of the frigate, and concealed from my
sight. By some means or other it was fired, and demolished the
schooner and three men, and blew the only one left alive overboard,
who was taken up very much hurt.

After this I fixed several kegs under water, charged with powder, to
explode upon touching anything as they floated along with the tide.
I set them afloat in the Delaware, above the English shipping at
Philadelphia, in December, 1777. I was unacquainted with the river,
and obliged to depend upon a gentleman very imperfectly acquainted
with that part of it, as I afterwards found. We went as near the
shipping as we durst venture; I believe the darkness of the night
greatly deceived him, as it did me. We set them adrift to fall with
the ebb upon the shipping. Had we been within sixty rods I believe
they must have fallen in with them immediately, as I designed; but,
as I afterwards found, they were set adrift much too far distant,
and did not arrive until, after being detained some time by frost,
they advanced in the day-time in a dispersed situation, and under
great disadvantages. One of them blew up a boat with several persons
in it who imprudently handled it too freely, and thus gave the
British that alarm which brought on the battle of the kegs.

BUSHNELL’S SUBMARINE.

A A. Oars. B. Rudder. C. Seat. D. Immersion tank. E. Pipe. F.
Conning tower. G. Safety weight. H. Torpedo.
]

The above vessel, magazine, &c., were projected in the year 1771,
but not completed until the year 1775.

The above account appears in the fourth volume of the Transactions of the American Philosophical Society, and also in the fourth volume of Nicholson’s Journal of Natural Philosophy (1801).

Disappointed in the failure of his submarine boat to accomplish the things of which he felt sure it was capable, Bushnell went to France, and finally settled in Georgia, where he lived under the pseudonym of Dr. Bush until the year 1826, when he died at the ripe age of ninety.

General Washington, in a letter to Thomas Jefferson dated September 26, 1775, described Bushnell as “a man of great mechanical powers, fertile in inventions, and master of execution.” With regard to the submarine vessel he says, “I thought, and still think, that it was an effort of genius, but that too many things were necessary to be combined to expect much from the issue against an enemy who are always upon guard.”

Bushnell was undoubtedly the first inventor who combined in his design submarine navigation and torpedo warfare, and his invention, crude though it was, was the embryo of the modern diving torpedo-boat. The principles on which it was built may be traced in almost all the later submarine craft, and the improvements that have taken place have been mostly due to the general progress of engineering; the “oar placed near the top of the vessel” may be compared with Mr. Nordenfelt’s vertical screws.