CHAPTER XIX.
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.