parallelopiped, not above 18 or 20 inches in the side of the square; into which the person should let himself down by steps nailed to the side: for in so small an area the motion of the water would sooner subside; neither would the librations be any thing near so large as on a smaller surface. One of the reasons, that induced me to make these experiments, was a desire of knowing what quantity of fir or oak timber would be sufficient to keep a man afloat in river or sea water, thinking that most men were specifically heavier than river or common fresh water; but the contrary appears from these trials: for, excepting the first and last, every man was lighter than his equal bulk of fresh water, and much more so than his equal bulk of sea-water: consequently, could persons, who fall into water, have presence of mind enough to avoid the fright usual on such accidents, many might be preserved from drowning; and a piece of wood, not larger than an oar, would buoy a man partly above water so long as he had spirits to keep his hold. Some things herein advanced will perhaps more readily appear from the following relation. The Lords of the Admiralty have appointed, for the exercise of the scholars belonging to the royal academy at Portsmouth, a small yacht; wherein, during the summer months, those young gentlemen are taught the practice of working a vessel at sea, under the directions of one of the master-attendants, assisted by eight or ten seamen. The last time this yacht was out, which was about the beginning of last October, one of the scholars was ordered to heave the lead. The youth was about thirteen years old, small of his age, and far from being fat; as he was stepping on the gunnel, he fell over-board: the sea was rough, and the yacht had great way; so that he was presently at a considerable distance from the vessel. The skiff was immediately let down; but the painter not being fast, the rope run an end, and the skiff went adrift. One of the seamen jumpt over-board, got into the boat, brought her along-side the vessel, took in another man, and then went after the youth, whom they recovered, after he had been in the water more than half an hour. The young gentleman, relating the affair, said, that as he could swim very little, and judging he should sink if he strove against the waves, he turned on his back, and committed himself to their mercy. He kept himself perfectly calm; and observed, when a wave was likely to break over him, to hold his breath, and to spurt out the water forced into his mouth. His hat, which happened to be tied by a piece of string to one of his coat button-holes, he often held up with his hand, as a signal where he was. Just before the boat came up to him he began to be faint, his eyes became dim, and he thought himself on the verge of sinking. This youth, who, by his prudence, saved himself from drowning, must, at that time, have been specifically lighter than water.