Page:Popular Science Monthly Volume 9.djvu/142

124 next cause of monstrosities mentioned was such as operated directly on the fœtus in utero. The generative matter may be perfect and fully representative, but certain morbid influences may act directly on the fœtus. Dr. Armor instanced the experiments made in producing malformations by submitting hens' eggs to various mechanical influences during incubation. In conclusion, he held that all causes of malformation would come under one of two heads: They are either generative or mechanical—sometimes one operating, sometimes the other, sometimes both.

Habitat of the Crocodile.—Till recently the two American species of crocodile, described by Cuvier, have been supposed to be confined to South America and the West Indies. In 1870 Prof. Wyman identified a skull from Florida as belonging to Cuvier's species, Crocodilus acutus. Mr. William T. Hornaday now describes in the American Naturalist two specimens—male and female—of the Crocodilus acutus which he captured last year in the vicinity of Biscayne Bay, on the southeast coast of Florida. The male was fourteen feet in length, and his girth at a point midway between fore and hind legs was five feet two inches. His teeth were large and blunt; his head rugose and knotty, with armor-plates very large and rough. On dissection it was found that during life he had sustained serious bodily injuries, probably in battle. Three of his teeth were shattered; the tibia and fibula of the right hind-leg had been broken in the middle and again united, also one of the metatarsal bones of the same limb; the tail had been docked, and two of the vertebrae had grown together solidly.

The female measured ten feet eight inches. Her head was regular in outline, comparatively smooth, with white, regular, and sharp plates, even in surface and contour, and colors very marked. The entire under-surface of both specimens was pale-yellow, shading gradually darker up the sides with fine irregular streaks and spots of black. The general appearance of the female was decidedly yellowish, while the back and tail of the male showed an almost entire absence of yellow, the prevailing color being a leaden, lustreless black. While in Florida the author saw the skulls or other remains of three other crocodiles. He observes that all the specimens were taken in water that is brackish about half the time.

Effects of Strain on the Magnetism of Soft Iron.—The following account of experiments made by Sir William Thomson, with a view to ascertain the effects of stress upon the magnetism of soft iron, we take from the Telegraphic Journal. Wires of steel and of soft iron, about twenty feet long, were suspended from the roof of the physical laboratory of Glasgow University. An electro-magnetic helix was placed around a few inches of each of the wires, so that the latter could be magnetized when an electric current was passed through the former, the induced current thus produced in a second helix outside the first being indicated by a second galvanometer. With steel wire, the magnetism diminished when weights were attached to the wire, and increased when they were taken off; but with "special" soft-iron wire (wire almost as soft as lead), the magnetism was increased when weights were put on, and diminished when they were taken off. Afterward he discarded the electrical apparatus; and, by suspending a piece of soft wire near the magnetometer, consisting of a needle a small fraction of a grain in weight, with a reflecting mirror attached, the wire was magnetized inductively, simply by the magnetism of the earth, and changes in its magnetism were made by applying weights and strains, the changes being then indicated by the magnetometer.

The Origin of Astronomy.—Like that of many other sciences and arts, the origin of astronomy has been ascribed to various nations of antiquity, and it is very doubtful if any one of these can lay exclusive claim to the credit of having been its founder. The succession of day and night and of the seasons, the phases of the moon, and the motions of the heavenly bodies, must have enlisted the attention of man from the earliest times and in every clime. The result would naturally be a more or less perfect system of astronomy. Some nations, no doubt, from one cause or another,