Page:Popular Science Monthly Volume 2.djvu/655

Rh A Spider's Engineering.—A writer in Hardwicke's Science-Gossip saw a spider's web stretched across a small mill-stream, and attached on either side to stems of grass and other herbage. The stream was about three feet in width, and the web resembled a cart-wheel in general outline, having a diameter of at least six feet. The writer asks how "an animal that neither flies, leaps, nor swims," could accomplish such an engineering feat. But is it true that the spider does not swim or leap? In fact, the animal can run on the surface of water, can leap from place to place, and can float after the manner of Mr. Home the medium. It can even dive in water. But, further, it can swing like a pendulum, suspending itself like a thread from some elevated point. The writer in Hardwicke does not tell whether there was any object near the web on either margin of the stream of sufficient height to allow of the animal's so swinging from one side to the other.

Geology of the Great Plain of Morocco.—The Journal of the Geographical Society (British) has a paper by George Man, F.G.S., on the geology of Morocco, of which we give the substance. The plain of Morocco rises 1,700 feet above the sea-level, and is covered with a tufaceous crust, from a few inches to three feet thick, which is burnt for lime near the city of Morocco. The underlying rock is of similar composition but not so hard, and is called by Mr. Man a "cream-colored limestone and gray marl of cretaceous or tertiary age." Midway between Mogador and Morocco are flat-topped hills 200 or 300 feet high, covered with tabular masses of chalcedony. This suggests an enormous erosion of the plain. The author contradicts Rolfe and others who assert that snow remains upon Mount Atlas during the entire year, and says that in the first week of May snow was to be found only in deep gullies and in drifts. The mass of the Atlas range is mainly composed of porphyrites and porphyritic tufas, overlaid by cretaceous rocks, with basalts rising in erupted dikes and masses evidently post-cretaceous. Metamorphic rocks appear in rugged hills near Morocco, and white limestone on the high Atlas. Glacial moraines may be seen on this range nearly 8,000 feet above the sea, forming gigantic ridges and mounds of porphyritic blocks, in some places damming up the ravines; and at the foot of Atlas are enormous mounds of bowlders. These mounds often-times rise 2,000 feet above the level of the plain, and according to Mr. Man were produced by glaciers. Of marine drift no trace is visible.

Cross between the Zebu and European Cattle.—The organ of the Royal Prussian Agricultural Department contains a notice of some experiments on the cross between the zebu, or Indian ox (Bos Indicus), and European cattle, by W. Nathusius-Konigsborn. The doubts that have existed in regard to the fecundity of this cross led to the experiments which, the writer thinks, must forever set the question at rest. The male zebu made use of was a yearling calf from the Zoological Gardens, of the peculiar bluish-white color characteristic of the zebu race. Four heifers of Holland stock were got with calf by this animal, and produced two heifers and two bull-calves, all of which were successfully raised. Though the dams were variously colored, all the calves had white stars in their foreheads. When they arrived at suitable age, they were bred with each other and with other cattle, and both sexes proved in every respect capable of propagating their race. The amount of milk given by the half-bloods was about 500 quarts per annum. This was so much below the ordinary average as to prevent all hope of their being a desirable breed. In addition, the oxen, from which much was expected in speed and endurance, proved so incorrigibly obstinate as to defy all efforts to train them for the yoke, lying down on the smallest provocation, and in one case, where it was necessary to lead one of them a short distance, the animal died the next day, it was supposed from the effects of anger and excitement. They acted much more like half-tamed wild-beasts than like domestic cattle. The only redeeming feature was the quality of their flesh, which, in those that were sent to the butcher, proved to be excellent.

Solidifying Petroleum.—The Journal de Eclairage au Gaz describes as follows a