Perseverance Island

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.

CHAPTER XX

Launch the submarine boat. Experiment with it in Stillwater Cove.

Having completely finished and arranged my boat, my next task was to launch it and arrange for a series of experiments to ascertain its practical value. So one fine morning I went forth, with a beating heart, from the Hermitage, and waited patiently till nearly high water, and having greased my launching ways, and confined the cradle with a long and strong rope of rawhide, so that its momentum, when launched, should not carry it across Stillwater Cove without being checked before it reached the other side, I, with anxiety and almost fear, withdrew the iron bolts in front of it on the ways, and, going to the upper end, applied a crowbar to the still stationary mass, and after a few motions of the bar it began to move, and with one grand rush, not very fast, and yet majestic and striking, the cradle, with its precious freight, dashed into the water, and, being brought up by the long rope of rawhide fast to it, in a moment or two rested quietly upon its bosom.

I took the canoe "Fairy" and paddled all about it and saw that it sat well balanced, and secure, and that it floated beautifully. I then made fast to it with a short piece of rawhide rope, and commenced towing it to the mouth of Stillwater Cove, where the water was deep but smooth, to still further carry on my experiments. It was a good hard day's work to tow the heavy cradle to the place that I had fixed upon, which was at the mouth of Stillwater Cove, just within the breakwater, and about one mile beyond the landing-place and two or three miles from the Hermitage. This place was admirably fitted for my purposes, the shore being of a smooth sand and the water gradually deepening towards the centre of the cove. Nothing but clear, pure sea-sand on the bottom, and no rock to injure the boat or interfere with any experiment I might choose to make. Having arrived, I was glad to anchor the whole concern safely, and to make my way home in the canoe.

The next day, fitted out with all I thought I should need, including my two goats for the treadmill and provisions for a day or two, I made my way back again in the canoe to the floating cradle. I found everything all right, as I had left it, and proceeded to prove the practical efficiency of my invention. In the first place I took the goats on shore and tethered them, so that they could feed, but not escape. I then went to work and anchored the cradle in about twelve feet of water, it then being nearly low tide, or slack water. After having secured both it and the boat also, I went to work sawing off the slats of the cradle upon which the latter rested, and in less than two hours the last one was off, and I had the satisfaction of seeing my boat floating in the water, drawing only a few inches, certainly not over six, with the manhole open, sustained wholly by the confined air in the tanks, which held up the superstructure bravely. After the slats were cut away I drove out the pins from the mortised framework of the cradle and left my iron boat floating calmly on the bosom of the smooth waters of Stillwater Cove. Floating the timbers to one side that had formed the cradle, I allowed them to drift up stream with the now incoming tide, the boat being securely anchored by two anchors, one in advance and one at the stern, which were made fast to two ringbolts on the roof, placed at each extremity.

And now for my final test. I had made up my mind, if the thing was not a success, that I did not intend to be personally implicated in any disaster. Two things only could happen; one, that the boat might capsize, and if so I was prepared to go on board with little clothing, so that if it vomited me up I could easily reach the surface and then swim ashore, which was distant only a few rods; the other, that I should be unable to improve my air, once vitiated or used up. In the latter event I had only to dive out from under the boat and again make my way to the shore, losing, however, the lives of my poor goats.

I commenced my work by going on board of the boat by means of a short ladder, which reached from the manhole to the deck beneath. In the first place I shipped or hung the wooden shelves on each of the tanks, and loaded them with several iron weights, and also large smooth stones and the two anchors that belonged to the boat. This made it very firm, and sunk the tanks at least two inches more. I then went on shore and brought off my goats in the canoe and passed them on board through the manhole, which I had made large for this very purpose. I then went to work in the interior and fixed my compass, steering-gear, treadmill, and propeller, taking great care to see that my spray-wheel was all in order, and at hand ready to be hung.

I also conveyed on board some candles, flint and steel, matches, and provisions, and as the last thing took in the stern anchor, so that the boat lay with the tide, tailing up stream. The other hawser I conveyed also – by means of the canoe and with a boathook – under the forward tank, so that I held the end within the interior, and could cast it off at anytime. It was by the sun about eleven o'clock when I gave one glance around me, and, standing on the last round of the ladder, I drew the manhole cover over my head and commenced screwing it down on the inside, which having done I lighted several candles, although I had a fair light reflected from the water and the bottom of the cove, formed of white sea-sand, directly beneath me, and distant, I should judge by the state of the tide, some twenty to twenty-five feet. My goats had become so accustomed to the boat that they showed little surprise at the rather dim light, and stood ready to perform their part whenever I should put them to their customary task.

My heart beat rapidly, not with fear, but with excitement and expectation. Here I was, already shut out from the outer air, and in a little world of my own. I hesitated to complete my experiment, and before going further I turned to my provisions and took a good long drink of claret wine to strengthen my courage and steady my nerves. If I was in a scrape I could get out of it, but my poor goats! they, I was afraid, would have to pay for any error in judgment on my part. Having regained perfect composure, I made up my mind to make the first test of the practical value of my boat, and that was to see if I could descend to the bottom of the ocean, that lay beneath me. By moving around I felt convinced that my calculations about the centre of gravity had been correct, and I felt that the boat would not capsize. It was remarkably stiff and steady, and would, I felt confident, remain so when submerged. This bugbear was already off my mind, and gave me confidence to proceed. So, moving to the place on the starboard side where all my pipes and stopcocks were congregated, I commenced by opening the stopcock of the water-pipe, which, as I had foreseen, brought no perceptible change. Some little water rushed into the tanks, but only what was sufficient to compress the air to the extent of the weight of the superstructure of the boat. This experiment did not sink it one particle; its buoyancy remained exactly the same, for the same air remained in the tanks, although compressed, and was not able to escape on account of the position of the outlet of the pipe that had opened communication between it and the water, pointing, as it did, directly to the centre of the earth. After waiting a little, and seeing that this all worked well, I placed my hand upon the stopcock of a more important pipe, namely the tank air-pipe, which led from the tanks to the outer surface of the superstructure.

Now, or never! Upon turning this cock I should descend or my theory would be incorrect. The moment my hand opened this valve the air would be expelled by the pressure of the boat upon the water, conveyed to the air in the tanks by the water-pipe, which was already open; and, as it was expelled, so the buoyancy of the boat would be decreased, and I should descend. The fatal moment had come, and with a firm hand I opened the tank air-pipe, and plainly heard the escaping air, the incoming water, and felt the boat descending, and saw the sandy bottom apparently approaching me. I cut off the discharge of the tank air-pipe, and with a slight rebound the boat arose again a few inches towards the surface, simply regaining its true position in equilibrio, that it had for a moment passed, by the momentum of its descent. By little turns of this stopcock I discovered, as I expected, that I could move the boat in a descending direction even an inch at a time. The movement was a perfect fascination, but each delivery of air was bringing me nearer the bottom, and as yet I had tried no means of rising again to the surface.

When I had gotten to within about six feet of the former I thought it time to see if I could again rise towards the surface. I was well aware that, having used up this air, it was so much loss to me, but I was in hopes to be able to replace it; and even if I could not replace it to make the boat rise to near the surface without it. I could do this in one way, by casting overboard the anchors and weights lying upon the wooden shelves; but this, if done to any great extent, might cause the capsizing of the whole affair. No; I had a better way than this, and at it I went. In the first place I closed the water-pipe, and then, having opened the screw-valve in the connected tanks, I screwed upon it the pump and commenced discharging the water from them – that had run in to take the place of the discharged air – into the water of the ocean, which formed, in one sense, the interior flooring of my boat.

To make this pump work I of course opened, and left open, the pump-pipe, so that the air from the interior rushed in and filled the tank as fast as the pump discharged the water, and at each stroke of the pump, after the first few, the boat, as I had hoped, began to rise; the water, having been just so much ballast to carry it down, being discharged by the pump, was just so much thrown overboard in weight to allow it to rise. By persistent pumping I made my boat rise quite near the surface, but not to the buoyant position it at first maintained, for I had in my descent used up considerable of the air in the tanks, which I had as yet not replaced, or rather what I had used from them had been replaced from the air of the interior when I pumped out the water, which I could only do by allowing the connection between the tanks and the interior to be open, so as to make the pump work. In short I had lost just so much buoyancy as was equal to the escaped air; but still I had been able to make the boat descend and ascend.

These experiments took me over two hours, and I commenced to feel the need of new air, and to notice that my candles began to burn a little dimly. I was thus warned that my air was being used up and charged with carbonic gas, and that it was time for me to renew it. So I unscrewed the pump and closed the valve, opened the water-pipe, and placed my hand upon the tank air-pipe and prepared to descend. One effect I should have noticed of my loss of air, and that was that the water in the interior of the boat rose considerably, and a large portion of the tanks was now submerged. A few turns of the stopcock of the tank air-pipe carried me near to the bottom, where I desired to be, to try my last and most important experiment.

Arriving to within a few feet of the bottom I rigged my spray-wheel, and connected it with the drum of the treadmill and set the goats at work. And it was time, for my breathing had become oppressive, and the animals themselves seemed dull and frightened. I had waited almost too long. My candles also commenced to burn more dimly, and I prepared to take my plunge into the water and come up outside of the boat should my experiment now fail. But wonder of wonders! my spray-wheel made but a few revolutions, dashing large quantities of minute spray into the interior by its rapid motion, before my lungs were relieved, the candles renewed their brilliancy, and the goats recovered from the lassitude under which they had a moment before seemed to be laboring.

The problem was solved. I had made my own air. I could remain below the surface as long as I desired. Everything about me was rather damp and moist from the dashing of spray about the interior, and several of the candles, that I had not protected, were put out; but two, in the extremity of the boat, were preserved, and now that my problem was solved I did not again light the former, the two remaining ones being all-sufficient. And in fact I did not need them; my own lungs, I found, were sufficient as a guide to tell me in future when to renew the air. Still it was fascinating to see these two candles burning brilliantly that had but a moment before been so dim. The reflected light from the pure sandy bottom just below me was amply sufficient for all purposes.

I imagined, by the slight shadow that the boat cast on the bottom beneath, from the brilliant sun that I knew was shining overhead, and from counting up in my mind all I had done since leaving the surface, that the air had lasted me, as nearly as I could judge, two hours; and that seemed to be the extreme limit to which I could go and not renew it. I also knew by the quantity of tallow consumed in the candles that it must be nearly that amount of time. I also noticed that the spray-wheel had not only purified my air, but that whilst it was in operation the boat had slightly ascended, proving that I had gained a lighter gas for the nitrogen and carbonic acid precipitated.

One more thing remained to be tested, and I should feel that my labors were complete. In the first place I made the boat ascend as far as possible, by means of the pump and stopcocks, as before described, and then I went to work and rigged my propeller and set the goats at work. I got the boat as near the surface as possible before communicating motion to it, so as not to run against any obstacle if possible. But then the body of water in which I was submerged was so pure, and free from anything of that nature, that there was little danger after all. With a feeling of confidence that I had not had in all the other experiments, I cast off the hawser affixed to the anchor that held the boat, and started the goats. Mechanics did not trouble me, and it was with no surprise, but only gratification, that I saw by the bottom that the boat was moving forward, and that it readily obeyed the helm. I turned it completely around by the tiller, and made an excursion of fully half a mile, I should think, up Stillwater Cove, once in a while getting out of the channel, when by stopping the goats and reversing the propeller I was able to back into the channel again, and finally to turn around by a series of forward and backward motions till I again arrived at the place from which I had started, which I knew by the anchor lying in mid-channel. By observation of the bottom I should say that the boat was propelled at least three miles an hour, which was sufficient for all my purposes.

After arriving back to my first position I pointed the boat towards the sandy beach, and when the hanging shelves touched the bottom I carefully removed them and their weights to the top of the tanks, in the interior, and, with a short pole, pushed the boat still nearer the shore, till the tanks rested on the sand; and this I did with care and quickly, for I was a little afraid of a capsize when the hanging shelves were removed, which was only for a moment or two, however, before the boat was at rest on its own foundations, on the sand. I then forced down under the water from the interior quite a large block of wood under the tank that had the water pipe protruding, so that the latter should not be hurt by being driven into the sand when the whole boat was stranded at low water.