Construct a submarine boat, to be propelled by goat power and to make
its own air, to examine the bottom of the ocean near the island for
pearl-oysters.
Yes, as I have hinted in the preceding chapter, I had fully made up my
mind to explore the _bottom_ of the ocean that surrounded my island,
and I did not intend to commence in the stupid way in which the former
Crusoe went to work, and build me a boat and then be unable to launch
it. Far from it. My very first care was to erect ways running down
into Stillwater Cove, made out of large square timbers, placed at a
considerable decline, so that I felt confident that what I should erect
upon them could be launched by me into the water without difficulty
or trouble. These ways I bolted strongly together, and made firm and
enduring, and upon them erected a kind of raft, which I kept in place
by means of upright iron bolts through the timbers of the ways, which
prevented it, for the time being, from slipping into the water if it
should be so inclined, but which, when the bolts were removed, and the
three timbers upon which it rested well greased, I felt sure would, at
the proper moment desired, slip into Stillwater Cove.
Upon this raft I commenced to construct my submarine boat. These
launching-ways were erected near the smelting house, and not far below
the falls, just where the water became deep enough for my purpose, and
yet as near as possible of access to my forge and shop. The raft that
I built and erected upon the ways was only as a cradle to support my
submarine boat so that I could float the whole affair to the mouth of
Stillwater Cove before allowing the latter to be submerged; for where
I now was there was not water enough for my experiment, and I well
knew that if my boat, which was to be of iron, was once launched, and
should, by its displacement or specific gravity, go to the bottom, that
I should be unable to raise it again, and that in the water directly
in front of the ways it would touch the bottom even before it would
be submerged. On the other hand, if I should erect my ways running
into deep water at some place near the mouth of Stillwater Cove, and
opposite Point Deliverance, I should have no means at hand to complete
it, all my forges, iron-work, tools, and shop being too far distant for
such an undertaking. I saw, therefore, that I must construct it near
to my foundry, and hence I chose this method of a cradle, or raft, to
carry out my plan. This raft, or cradle as I shall call it in future,
was of itself quite an undertaking, for I had to make it of mortised
pieces of wood, so that at the proper time I could take it to pieces,
and allow its load, the submarine boat, to drop into the ocean, at some
place yet to be determined, to which I should tow it, where the water
would be smooth, and protected from the billows of the ocean, and not
too deep for my experiment.
I had also another care in forming this cradle, and that was, that
it should be buoyant enough to sustain the submarine boat, and not,
when launched, go to the bottom of Stillwater Cove with its precious
freight, on account of the weight of the latter. This cradle,
therefore, took both time and care to make, and long hours were passed
by me in figuring out the weight of the iron boat I was about to build,
and how large and extensive my cradle ought to be to sustain it. By
studying my book, and by experimenting in different ways with small
vessels of pottery and bladders blown up with air, that I submerged, I
got at what I thought would be about the weight of my submarine boat
and its relation to the cradle, and I saw plainly that the latter would
have to be improved in some way to sustain the necessary weight. So
this is how I went to work to overcome this obstacle.
On the two long sides of the cradle running parallel to the timber
ways, beyond which they extended several feet (although the ways
themselves were some six feet wide from the outside of one timber to
the outside of the other, by my island rule), I lashed firmly with iron
bands and bolts two water-tight iron tanks, which I constructed of my
rolled iron, riveted together, fully six feet long, three feet wide,
and three feet deep. The dimensions of the cradle itself were about
these: Ten feet wide and eighteen feet in length, resting firmly upon
the three declined timbers or ways, which were six feet wide from side
to side and some forty feet in length from where they commenced on the
shore to their terminus under the water in Stillwater Cove, at a depth
of about eight or nine feet at high water. They were kept in place by
their own weight, being of as large a size as I could handle with my
team of goats, and of hard-wood, the inclination they received from the
shore ends forcing the outer ends to the bottom of the water. Of course
these ways were not made of one piece of timber but of several, which
were as large as I dared cut them with any hope of being able to handle
them, and were fished together to make the required length, being first
sawed out at the mill, planed upon the upper side by hand, and then let
down again over the inclined planes of the mill into Rapid River, and
thence thrust over the falls into the shallow water and conveyed to
their place, where I pulled them on shore by means of rollers and my
team of goats, till I had each in place and mounted upon short uprights
of other timber, that I had placed at equal distances from each other,
and higher one than the other as they were erected landward from the
water.
The underpinning of my cradle was exactly like the wooden underpinning
of a house, and consisted of a parallelogram, eighteen feet by ten
feet, with timbers of about eight inches square. Across these timbers
were placed smaller ones in sockets, exactly as slats are placed
across a bed, and this was to form the foundations upon which I was to
erect my boat.
When I desired to submerge it I had only to saw away each of these
slats, on either side, and it would drop into the ocean, leaving the
outer framework--or bedstead, if you please--floating; for my boat was
to be built, of course, less than eighteen feet long and ten wide, so
as to rest wholly upon these slats and not upon the framework of the
cradle that supported the slats. This took me a long time to finish;
but what was time to me whilst revolving the problem of my escape,
which was not yet solved. Till I knew _how_ I was to escape I should
never again be in a hurry.
To build my boat I commenced by making two watertight tanks, each
sixteen feet long and two feet square, and two smaller ones, each six
feet long and of the same dimensions otherwise as the long ones; these,
placed upon the slats of my cradle, gave me a parallelogram composed
of four water-tight tanks, all made out of my rolled iron and riveted
together firmly. I had to erect a derrick to hoist them into place, but
once in the cradle I had only to bind the two ends of each extremity of
the long tanks to the short ones placed at right angles to them and I
had the foundations of my boat laid. I bound the small tanks in place,
as also the large ones, by bands of iron, several in number, which I
brought together on one side by means of what is called a turn buckle,
such as is often seen on iron bridges, both ends of the bands being
formed with a screw-thread, and fitting into this turn-buckle nut on
both sides, which could be then tightened by means of a lever, so as to
bring an immense binding force upon each band.
Upon the outer edge of this parallelogram of tanks I had left a sort of
comb of iron, some three inches in height, already pierced, or rather
punched, ready to receive the roof of the boat, also air-tight, to be
bolted to it, so that when all was done my platform of tanks would be
nearly two feet wide within the boat, and allow me plenty of margin to
rest any kind of a movable platform upon, or deck over the space that
was left open, some fourteen feet long by six feet wide.
The nearest description that I can give of this roof is, that it rose
in all directions at an angle of about forty-five degrees till it was
bolted to a large flat surface made up of several sheets of rolled
iron, which formed the top, which was ten feet long and four feet wide.
This flat roof was fitted with a manhole, somewhat large in proportion
to the rest of the boat, at least two feet square, and fitted over a
raised rib of iron, which was packed with greased milkweed floss, and
closed on the inside by set-screws, that were worked with a short iron
lever, so as to make the opening perfectly air-tight.
I commenced this chapter by saying that I did not intend to make such a
fool of myself as the old Robinson Crusoe did, and that I was not going
to make any errors either of judgment or figures; and yet I had not my
boat completed as far as I have described before I discovered that I
had been a silly ass, fully as silly as it was possible for a mechanic
to be, and one day it flashed upon me that my whole cradle, with its
air-tight chests, was an egregious folly; that I had not the least need
in the world for it, and that I had wasted time, labor, and patience
in perfecting it. Carried away, as I was, with the means I intended to
employ to sink and raise my boat I had totally overlooked the fact that
as now being built, and as it would be launched, that it would float
itself, the size of the four air-tight tanks being sufficient to float
five times the upper structure built on top of them.
As I am writing a veritable history, and no fable, it behooves me to
tell the truth, and it was with feelings of both mortification and
mirth that I surveyed my partially finished work. It was the mental
contemplation of a series of air-cocks, weights, pumps, etc., to be
hereinafter described, that had led me astray as to the buoyancy of
the boat as it now stood, and it was what I was going to use the tanks
for, rather than what they now were, that had led me to this error.
But then there was no great harm done. I had not to change the plan of
the boat in the minutest particular, and the cradle might after all
be advantageous in launching it, and preserve it from any casualty.
Therefore, with the exception of my loss of time, I was nothing the
worse; still I was rather crestfallen to think what a mistake I had
made. But after mourning for a short time I set to work with renewed
ardor to complete my task.
After having strapped the four tanks together and covered them with
the iron roof, as described, I went on to complete the remainder of
the boat, in this manner. In the interior, which I could easily reach
by getting up from underneath the ways through two of the slats of the
cradle, I arranged the following: The space in which I had to work was
about fourteen feet in length, six feet wide, and eight feet high from
the bottom of the tanks to the flat roof, which contained the manhole,
which, for the present I left open, to give me both light and air. In
the first place I connected all these four tanks together by means of
a half-circular arm of piping some three inches in diameter, which I
placed in each of the four corners of the parallelogram formed by the
interior of the boat, leading from one tank to the other, where the
latter met at an angle, so that the air that each contained was put
in direct communication with the others. These connecting pipes were
fitted in with a flange and riveted, and were placed a few inches from
the bottom of the tanks, thus making really one tank of the whole.
As the roof was fastened to the outside of these tanks, I had a seat
or margin running round all the sides of the interior two feet wide,
from the outer or further side of which arose the roofing. I could,
therefore, easily lay any kind of a movable deck over this open space
of fourteen feet by six feet, resting the ends of all my planks upon
the top of the tanks in any direction.
Having connected all the tanks so as virtually to form one, so far
as concerned being one air-chamber, I then went to work and pierced
the perpendicular side of one of the tanks quite near the bottom and
inserted a similar pipe to the horizontal ones that connected the tanks
at the angles. This pipe, however, was in the form of a right angle, or
rather its two ends were at a right angle, the bend being of a circular
form. It pierced the tank near the bottom, as I have said, extended in
a horizontal line some eight inches, and then gradually turned in a
circular manner till the other end, about one foot in length, pointed
downward, in an exact right-angle from the end entering the tank. This
was put on with a flange, and made water-tight, and in the top of it,
about three inches from the tank, was fixed a stopcock, with a long
rod, which arose inside the boat, parallel with the side of the tank,
till it ended in a handle, situated some ten inches higher than the
top of the tanks. Near this, also, I erected another piece of pipe,
which entered the top of the tank and pierced the roof of the boat,
which was also fitted with a stopcock. Still another pipe pierced the
roof, which was fitted with a stopcock outside as well as inside, and
depended down into the boat some four feet from the roof. These four
pipes, with their stopcocks, were so arranged as to be all near to each
other, so that I could control them all without moving in my position,
and were made at about the middle of what I called the starboard side
of my boat, though it would be hard to say which side starboard was,
as both ends of the boat were exactly alike up to the present time.
But as I was eventually to have a propeller and rudder, which would
define the stern, I had already concluded that the part of the boat
nearest the water should be the bows, and hence I knew which to call
the starboard side and which the port side. Added to the pipes and
stopcocks already enumerated was one which was simply about a foot in
height, which pierced the tank on the top, some few inches from the
inner edge, and near the others. It was also fitted with a stopcock,
and, that my readers may fully understand the uses to which I put all
these appliances at a later day, it will be well, perhaps, to name
them, so that when used it will be possible to understand to which of
the numerous ones I refer; and to prevent confusion, and to make myself
understood, I will say that the pipes at the angles of the tanks I
took no note of, they not being fitted with any cocks, and only made
to connect all the tanks together, so that any action I might make
with any of the stopcocks would be communicated to the whole system of
tanks, of which the foundations and main part of the boat was formed.
The pipes with stopcocks I named as follows: The one leading down into
what would be the water when the boat was launched, and below the
bottom of the tank some inches, fitted with a long rod and handle, I
called the water-pipe and stopcock; the one that connected the tank
with the roof, the tank air-pipe and stopcock; the one that pierced the
roof and depended into the interior, the atmospheric pipe and outer
and inner stopcocks; the one that stood erect, ten inches in height,
the pump-pipe and stopcock. So that I had four pipes and five stopcocks
to my boat, all of which had their uses, as shall be related.
Besides all these four pipes I also made near to them an opening into
the tanks, which was fitted with a screw thread, upon which I could,
when occasion demanded, erect a quite large and powerful pump, that I
had made for the express purpose.
One more thing remained to be done, and that was to make all around
the boat inside a sort of movable step, that would ship and unship. I
was well aware that, unless the centre of gravity was kept well down,
my boat would capsize and spill out all the air when in use, and to
prevent this I made these movable steps, which it is difficult to
describe. They were made of an upright piece of wood that was over
four feet in length, and on the top of which another piece of wood was
nailed horizontally, some twelve inches in width, like one arm of the
letter T, whilst at the other end of the upright of four feet in length
was nailed another horizontal piece, some twelve inches in width, on
exactly the opposite side, like the letter L; so that when the whole
was done the upper horizontal board rested one foot on the top of the
tanks, whilst at the other end of the upright, two feet below the
bottom of the tanks, was the other horizontal board, facing in towards
the centre of the boat in all directions, and forming a kind of step
or shelf, upon which weights could be placed so as to prevent all
chance of the capsizing of the boat, the vomiting out of its air, and
perhaps the destruction of its constructor and inventor. I had this so
arranged that I could speedily ship and unship it in sections, for it
was of course greatly in the way, and of no use except when the boat
was launched.
I then completed my deck, which I made of light planks, marked and
arranged so that I could readily board over all the space in the
interior or leave part of it open. Upon further thoughts, some of this
deck I made permanent, leaving only a space of about six feet by four
open in the forward end, which I could cover or uncover.
I then entered upon another part of the programme, namely, the motive
power by which I was to move this submarine monster, but that I had
long ago solved in my own mind. For some months I had been practising
two fine young goats upon a treadmill fitted to their size and
strength, all the time having in view the end of using them to create
the motive power of my boat; and for this purpose I had left the
manhole two feet square so as to be able to take them down with me into
it. I now went to work and transported the treadmill to the boat, and,
having fixed it in place, I each day conveyed the goats on board and
set them to work, so that they might get used to it. They were already
used to the motion of the mill, and I noticed that with the precision
of step of their race they worked the rounds of the mill much better
than horses usually do, and they soon became accustomed to the boat
and worked rapidly and well, obeying the least word of command. In fact
they were to me almost companions, and it would be amazing to relate,
if I had time, all I have taught these really sagacious and gentle
creatures since I have been on the island; not these very ones of which
I am now speaking in particular, but several of their race. Perhaps
before I am through with my narrative I may give an idea of the many
interesting things which I taught them.
For a long time I allowed the mill to be turned daily, without making
up my mind just how I would connect it with the wheel or screw that I
foresaw that I should have to make to propel the boat. I at last fixed
upon a propeller, to work in the open space of water in the interior of
the boat, and which I readily set up with good strong gearing, that I
could as readily take down by hand when needful. By means of bevelled
gearing I obtained several revolutions of my propeller to one of the
balance-wheel of the treadmill, and I saw, as a mechanic, that my boat
would move forward, perhaps not very fast, but still at the rate of
three or four knots an hour, which would answer all purposes.
I had one more necessary thing to make, and that was a rudder, which
I connected to the outside of the rear tank of the boat, bringing the
tiller or steering rods into the interior of the boat under the bottom
of the tank. I took care to fasten the heel of the rudder, which was
quite wide, above the line of the bottom of the tank, so that if the
boat grounded it would not be injured or destroyed.
And now I came to the most important part of my boat, and, in fact,
upon the success of which, and practical application, rested the
actual consummation of all my efforts. It was to obtain a supply of
air whilst under the surface of the water without connection with the
atmosphere, from which I was of course debarred. This problem solved,
I had, I felt, the whole matter under control,--and let it not be
believed that I had proceeded thus far in my self-imposed task without
seeing a way out of this difficulty. The following every-day facts were
easily ascertained from my Book of Useful Arts and Sciences, and upon
the following conclusions I had based my invention. It is well known
that oxygen is the portion of atmospheric air which supports life,
and that it composes nearly twenty-two per cent of the same, whilst
nitrogen, the remaining portion, is incapable of sustaining life. It
is also well known that water also contains oxygen, in the proportion
of two parts to one of hydrogen, of which two gases water is composed;
or, in other words whilst atmospheric air holds only twenty-two per
cent of the life-giving principle, water contains about sixty-six per
cent, or, by weight, eight-ninths of oxygen to one-ninth of hydrogen. I
also ascertained that the specific gravity of nitrogen is 0.94, whilst
that of hydrogen is only 0.0692. Now if I could release the oxygen
in the water I could make new air and at the same time precipitate
the nitrogen and carbonic acid in the boat, that might be in the
atmosphere, that had accumulated by my repeated breathings. Now the
only problem to solve was evidently how to release this oxygen with
which the water was so freely impregnated, charged, or made up of,
and by the breathing of which fishes sustained life. And this is how
I set about to do it. I made a very light paddle-wheel, full six feet
in diameter, with many, but light arms, and only six inches across the
face of each paddle; this was arranged so as to ship inside the boat,
upon sockets arranged so that the lower paddles would just touch the
water, and was adjustable by set screws, so that the journals could
be lowered or elevated as the pressure of the water in the boat might
show itself, higher or lower, according to the depth the boat might
be at. By this arrangement I could have the paddles, which were more
like a set of large-teethed combs than paddles, dip just such distance
into the water as I desired. This wheel was connected by series of
light wheels to the drum of the treadmill, so that I could obtain many
revolutions of the water-wheel to one of the latter. My idea was this.
By violent motion of the extreme ends of my comb-paddles through the
water I intended to throw up into the interior of the boat a mass of
minute spray, that in that form would itself release the oxygen that it
contained, or at least a large part of it, and grant to my exhausted
air the vitality it needed by new oxygen, or the life-sustaining
principle, and at the same time precipitate the carbonic acid that
the used-up atmosphere might contain. By this simple contrivance I
intended to renew my air, and thus remain just as long below the
surface as I might desire. The test that I should have that my air
was becoming impure would be the dimness with which the candles would
burn, with which I was to furnish the boat; and if after the use of the
spray-wheel they again flashed up brilliantly, I should know that my
theory was correct.
I had only one more thing to make to complete the whole affair, and
that was a compass, which, having finished, I took within the boat
to see and note its variations from the true north on account of the
attraction of the iron, and to regulate it so that I might be aware
always of my true course, for upon the exactitude of this instrument
rested the responsibility of my ever again reaching land should I dare
to go out into the ocean, supposing that the boat should work according
to my desires and theory.
For light I had nothing but the light contained in the water and my
candles. I could only pass from spot to spot by compass alone, and in
case of utmost disaster plunge into the water within my own boat and
try to reach the surface by coming up outside. It was not my intention
to propel the boat near the bottom but only when near the surface. When
near the bottom a turn or two of the propeller would send me in any
needed direction.
A few blocks of iron to place upon my hanging shelves, and four anchors
with strong rawhide hawsers, completed the appurtenances of the boat,
and it was finished. By examination of my diary I found that I had been
just nine months and eleven days in completing it from the day I had
started to work upon the ways.