the line being held fast in the boat, at length stopped it, though not till the "strain" was such that the boat was in danger of sinking. The "bight" or loop of a rope being then passed round the fish, and allowed to drop below it, inclosed the line belonging to the sunken boat, which was found to be the cause of the phenomenon observed. Immediately the harpoon slipped out of the whale, and was, with the line and boat attached to it, on the point of being lost, when it was luckily caught by the encompassing rope. The fish being then relieved from the weight of the lines and boat, rose to the surface; and the strain was transferred to the boat connected with the disengaged harpoon. My father, imagining that the sunken boat was entangled among rocks at the bottom of the sea, and that the action of a current on the line produced the extraordinary stress, proceeded himself to assist in hauling up the boat. The strain upon the line he estimated at not less than three-fourths of a ton, the utmost power of twenty-five men being requisite to overcome the weight. The laborious operation of hauling the line in, occupied several hours, the weight continuing nearly the same throughout. The sunken boat, which, before the accident, would have been buoyant though full of water, when it came to the surface required a boat at each end to keep it from sinking. "When it was hoisted into the ship, the paint came off the wood in large sheets, and the planks, which were of wainscot, were as completely soaked in every pore, as if they had lain at the bottom of the sea since the Flood!" A wooden apparatus that accompanied the boat in its progress through the deep, consisting chiefly of a piece of thick deal, about fifteen inches square, happened to fall overboard, and though it originally consisted of the lightest fir, sunk in the water like a stone. The boat was rendered useless; even the wood of which it was built, on being offered to the cook as fuel, was tried and rejected as incombustible.

This curious circumstance induced me to make some experiments on the subject. I accordingly attached some pieces of fir, elm, and hickery, containing two cubical inches of wood each, to the marine-diver, and sent them to the depth of 4000 fect. Pieces of wood, corresponding with each of these in shape and weight, were immersed in a bucket of sea-water, during the

time the marine-driver, and its attached pieces were under water, by the way of distinguishing the degree of impregnation produced by pressure, from the absorption which takes place from simple immersion. On being brought up, they were all specifically heavier than sea-water; and, when compared with the counterparts, the clear effect of impregnation by pressure, was found to be 302 grains in the fir and hickery, and 316 grains in the ash. This experiment was repeated in latitude 78° 2′, on the 7th June 1817, by the immersion of twelve articles of different shapes and sizes, to the depth of 4566 feet. On this occasion, the apparatus was 30 minutes on its way down, rested 40 minutes, and took 36 minutes in drawing up, being altogether 106 minutes under water. The degree of impregnation produced on each of the different substances used in this experiment, is stated in the following Table.

This degree of impregnation is not surprising, when we consider that the pressure of water, at the depth to which these specimens of wood were sent, is equal to, at least, 2031 lb. or 18 cwt. 15 lb. on every square inch of surface.

These experiments were repeated on the 18th July 1818. Finding, on former trials, that pieces of fir wood sent down 4000 feet, were more impregnated with sea-water than others immersed only half that depth, I was in hopes that the degree of impregnation of similar pieces of the same kind of wood might be applicable as a measure of depth. If this were the VOL. I. NO. 2. OCTOBER 1819.

B b

case, it would serve a very valuable purpose, since all the plans hitherto contrived for measuring depths from a vessel, when sailing slowly, or drifting through the water, cease to be useful beyond 200 or 300 fathoms. With this view, I not only attached pieces of wood of different kinds, to the lead, and provided counterparts for immersion in a bucket of water; but I also fastened cubes of ash, from the same piece of timber, of about one inch solid contents, and of exactly the same weight, to the line, at intervals of about 500 feet; by the weight of which, when taken up, I could ascertain whether the increase of specific gravity was in any way proportionate to the depth. When the specimens of wood for this experiment were procured, a clear grained piece, of double the size wanted for sending under water, was prepared, and then cut in two, and the two parts dressed to the same shape, and to within a quarter of a grain of the same weight: one of these was then adopted as a principal, and fixed to the lead or line; and the other as a counterpart, and put into a bucket of water. The specimens affixed to the lead were eleven in number, and consisted of wood of dif ferent kinds, shapes, and dimensions: they were sunk to the depth of 6348 feet, and the line was almost perpendicular for nearly an hour.

Each piece of wood attached to the line, was taken off as hauled in, plunged in a basin of water, and conveyed into the cabin, where its weight in air and in fresh water was immediately taken. The interval between any two pieces was such, that I had just time to determine the specific gravity of one, before the next came up. On the arrival of the lead, the attached specimens were immediately immersed in water, and weighed as quickly as possible, together with their counterparts, which had been secured at the bottom of a bucket of sea-water, during the time the experiment was in progress.

The following Table exhibits the results of this experiment.

0.951

0.654 5868

0.986 1.165

0.951

0.654 5370

0.963 1.165

From this table we may observe, that the greatest increase of specific gravity, by pressure, in the specimens of the different kinds of wood submitted to experiment, was obtained by the fir; the next greatest by the ash; the next by the elm; the next by the oak; the next by the teak; the next by the hickery; and the least by the mahogany. The cork gained still less than any of the pieces of wood. The proportion of impregnation of the same kind of wood, in specimens of different sizes and shapes, is derived from the experiments made on the ash; and it is curious to observe, that the largest cube of ash, No. 14, and the parallelopipedon of the same, No. 10, received the greatest proportional increase of weight; while the smaller pieces received less and less additional weight, per cubic inch, as they decreased in size. Thus, No. 14. containing about 4 solid inches of wood, gained 145 grains per cubic inch; No. 13. of about 3 solid inches, gained 143 grains per cubic inch; No. 11. of 2 solid inches, gained 137 grains per inch; and the specimens of 1 inch, solid contents, gained from 127 to 135 grains. It is also a little curious, that the specimens sent to the depth of 2058 feet, were as much impregnated as those sent down above 6000 feet. The cube of ash, No. 11. consisting of 2 solid inches of wood, gained 137 grains per inch, at the depth of 6348 feet, while a similar specimen gained 138 grains, at the inferior depth of 3708 feet. In the same way, a cube of 4 solid inches gained 145 grains per inch, at the extreme depth; and 144 grains per inch, at the depth of 4836 feet. The degree of impregnation of the one-inch cubes of ash, produced by immersion to the depth of 2058 feet to 6348 feet, varies irregularly, but is evidently as great at the depth of 2058 feet, as under any superior pressure; so that it is probable that the greatest permanent impregnation by pressure, of such open-grained woods as ash, elm, fir, &c. is produced at the depth of 300 or 400 fathoms. Hence, it is clear that no use can be made of this effect of pressure, for determining the depth, unless it be within 2000 feet of the surface; and even in this limit, the results may be uncertain.

From a comparison of column VII. with XIII., and column IV. with xv., it appears, that an effect of the impregnation of the wood with sea-water, was to increase its dimensions, as well as