Page:Popular Science Monthly Volume 12.djvu/524

508 clock-work arrangement. In order to do this, he contrived a tortoise-shaped diving-boat of iron plate, which contained air enough to supply a man for half an hour. This boat was propelled by a sort of screw, and guided by means of a compass made visible by phosphorus. The torpedo was carried outside of the boat, but could be detached by the concealed operator within. It was connected by a line to a screw, which was to be driven into the bottom of the hostile ship. As soon as this was effected, the torpedo was to be cast off, when it floated against the vessel's side. The action of casting-off set the clock-work going and then the operator had time to retire to a safe distance before the catastrophe. This torpedo and submarine boat were actually tested against an English sixty-four-gun brig early in the War of Independence, but the attempt to blow up the vessel was unsuccessful. No further effort appears to have been made to turn this invention to account. Nevertheless, to Bushnell the honor belongs of having been the first to destroy a vessel by a torpedo. In an attack on the Cerberus frigate with a towed torpedo, he blew up a schooner astern of the frigate, and killed three or four men on board. This schooner was the first vessel ever so destroyed.

Human Stature.—Treating of "Human Stature," a writer in the Revue d’Anthropologie gives 1.585 metre (about 5.199 feet) as the lowest mean stature of males among the Esquimaux, while in some tribes of the same race the mean reaches the comparatively high figure of 1.708 metre (about 5.60225 feet). This flatly contradicts the belief that cold climates produce only men of low stature. Among the Lapps the mean stature of men is 1.535 metre, and of women 1.421 metre. The Fuegians, so far from being diminutive, are above the average stature of the human race. The Bushmen rank among the most diminutive, the average stature of both sexes being under 1.400 metre. The Akkas attain precisely the same average. The mean stature of six Obongo women, measured by Du Chaillu, was 1.428 metre. Neither the Negritos nor the Andaman-Islanders can compare for littleness with the Bushmen of South Africa. On the other hand, according to this author, the highest stature is attained by the Norwegians, in Europe, the Kaffirs in South Africa, some Indian tribes in North America, the Polynesians, and the Patagonians. The mean stature of the last-named people, according to the statements of the most trustworthy observers, is 1.781 metre (5.84169 feet); the mean of natives of the different Polynesian archipelagoes is 1.762 metre (5.77937 feet). The mean stature of the human race is about 1.600 metre (five feet three inches).

Artificial Ice.—We select from a report in the Lancet, on "Ice-making Machines," a description of a machine designed to produce ice on the large scale. A cistern, somewhat like a tubular boiler, contains some ether, which is the refrigerating agent. The vapor escaping from the ether is pumped, by a double-action air-pump, into a condenser surrounded by cold water; thence the ether, now once more liquid, flows back to the cistern. The evaporation of the ether causes the cistern to become intensely cold, and this cold is rapidly communicated to a strong solution of common salt, in which the cistern is immersed. The very cold brine so obtained is caused to circulate through flat, hollow, and vertical partitions of tinned copper, in a tank filled with pure water. Ice quickly forms in smooth slabs on the partitions, and is from time to time removed as the slabs acquire the requisite thickness. The ice so obtained is, of course, exceedingly pure, and is said to waste less and cost less than natural ice. In this machine the ether is condensed again and again with scarcely any loss, and the only expenses after the original outlay are, therefore, for rent, fuel, and labor.

Mineral Caoutchouc.—In presenting to the Academy of Natural Sciences of Philadelphia specimens of mineral caoutchouc from South Australia, Mr. Galloway C. Morris stated that the substance is found during the dry season in a limited area of country of a swampy nature in the Coorong district. It occurs in sheets from the thickness of writing-paper to about five-eighths of an inch. It is made into illuminating oil. Of