Figs. 5, 6, and 7 show why, in those days of rope cables, a ship was always breaking the cable where it bent at right angles just outside the hawse-hole. All the strain was on the outer strands of the rope at a bc, Fig. 7, and as they broke the others followed one by one. His remedy for this was to have a large wheel or pulley in the hawse-hole.

Figs. 8 and 9 show how a vessel with a leak at first fills very rapidly, so that the crew, finding they cannot gain on the water with the pumps, take to their boats. But if they would remain they would find after a while that the quantity entering would be less as the surfaces without and within became more nearly equal, and that the pumps would now be able to prevent it from rising higher. The water would also begin to reach light wooden work, empty chests, and water-casks, which would give buoyancy, and thus the ship could be kept afloat longer than the crew at first expected. In this connection he calls attention to the Chinese method of watertight compartments which Mr. Le Roy had already adopted in his boat on the Seine.

Fig. 12 is intended to show the loss of power in a paddle-wheel because the stroke from A to B is downward and from D to X upward, and the only effective stroke is from B to D. A better method of propulsion, he thinks, is by pumping water out through the stern, as shown in Figs. 13 and 14.

Figs. 15, 16, 17, 18, 19, 20, 21, and 22 illustrate methods of making floating sea anchors by which to lay a vessel to in a gale. Fig. 24 shows how a heavy boat may be drawn ashore by bending the rope from

C to D. Fig. 23 represents a new way of planking ships to secure greater strength, and Figs. 26 and 27 are soup-dishes which will not spill in a heavy But this delightful letter is published in all of the editions of his works, and should be read in order to render his ingenious contrivances intelligible.

sea.

Among the few of Franklin's writings on scientific subjects which are not in the form of letters is an essay, entitled "Peopling of Countries," supposed to have been written in 1751. It is in part intended to show that Great Britain was not injured by the immigration to America; the gap was soon filled up; and the colonies, by consuming British manufactures, increased the resources of the mother country. The essay is full of reflections on political economy, which had not then become a science, and the twenty-second section contains the statement that there is no bound to the productiveness of plants and animals other than that occasioned by their crowding and interfering with one another's means of subsistence. This statement supplied Malthus with the foundation for his famous theory that the population of the earth increased in a geometrical ratio, while the means of subsistence increased only in an arithmetical ratio, and some of those who opposed this theory devoted themselves to showing error in Franklin's twenty-second section rather than to disputing the conclusions of Malthus, which they believed would fall if Franklin could be shown to be in the wrong.

He investigated the new field of political economy with the same thoroughness as the other depart

ments of science, and wrote on national wealth, the price of corn, free trade, the effects of luxury, idleness, and industry, the slave-trade, and peace and war. The humor and imagination in one of his letters to Dr. Priestley on war justify the quoting of a part of it:

"A young angel of distinction being sent down to this world on some business, for the first time, had an old courier-spirit assigned him as a guide. They arrived over the seas of Martinico, in the middle of the long day of obstinate fight between the fleets of Rodney and De Grasse. When through the clouds of smoke he saw the fire of the guns, the decks covered with mangled limbs and bodies dead and dying, or blown into the air, and the quantity of pain, misery, and destruction the crews yet alive were thus with so much eagerness dealing round to one another, he turned angrily to his guide and said, 'You blundering blockhead, you are ignorant of your business; you undertook to conduct me to the earth and you have brought me into hell!'"No, sir,' says the guide, ‘I have made no mistake; this is really the earth, and these are men. Devils never treat one another in this cruel manner; they have more sense, and more of what men (vainly) call humanity.'" (Bigelow's Works of Franklin, vol. vii. p. 465.)