Democratic Sentinel, Volume 7, Number 27, Rensselaer, Jasper County, 3 August 1883 — SCIENTIFIC MISCELLANY. [ARTICLE]

SCIENTIFIC MISCELLANY.

Air electric signal apparatus on a i French railway causes the blowing of a steam whistle upon a locomotive approaching a danger signal. The engineer is thus warned. This apparatus is found ! valuable in fogs ana snow-storms, j when ordinary signals often escape notice. The number of varieties of insects is vastly greater than that of all other living creatures. The oeh supports 450 species of insects, and 200 are found in the pine. Humboldt, in 1849, calculated that between 150,000 and 170,000 species were preserved in collections, but recent estimates place the present number at about 750,000 species. It is a very general belief that great burial places exert a noxious influence, which must raLder the localities very unhealthy es places of residence. This idea is shown to be a mistaken one by the results of any inquiry into the sanitary condition of the cemeteries of Paris. The composition of the air in the cemeteries is reported to be indistinguishable from that of arable lands. Concerning the moon’s effect on tides, the Astronomer Royal for Ireland receutlv stated that, while the day is gradu&Jly lengthening through lunar action tides, the earth reacts on the moon and drives it away farther and farther. Looking backward, the moon must have been nearer and nearer the earth, and at one epoch in the remote ages of the past—perhaps about 50,000,000 of years ago—the, two bodies must have been very close together. Then the day was but three hours long instead of twenty-four. At that distant period, the earth rotated onfte every three hours, and the moon revolved with it in the same time. So near was the moon that, if there had been oceans in those days as now, the tides must have been 216' times as great as at the present time; and, rising to an immense height, would ! have swept over the whole of England. Animal life in the Sahara is somewhat peculiar to the region, and, according to M. Vogt, the traveler is struck with the absence of all bright colors in the animals of the desert. As a rule, their hue approaches that of the ground, and the adaptation is most remarkable in birds, reptiles, grasshoppers, etc. Black and white exist in some animals—for instance, the male ostrich—which have nothing to fear from enemies; and a 3ingle exception to the rule occurs among insects the Coleoptera are nearly all black. To explain the existence in safety of these insects whose : color must make them conspicuous. M. Vogt states that they feign death on the approach of danger and in that state ! closely resemble the excrements of gazelles, goats, and sheep. This description, wi% their disagreeable odof, gives them sufficient protection. The general color of the ground to the desert u, of course that of sand. At the Crystal Palace, London, a second international electrical exhibition is to follow closely on the heels of the first at Paris. The objects to oe exhibited are chiefly compared in these classes : Apparatus used for the production and transmission of electricity and magnets, natural and artificial; mariners’ compasses ; lightning conductors, and applications of electricity to telegraphy and the transmission of sounds, to the production of heat, to lighting and the production of liprht, to the service of light-houses and signals, to apparatus giving warning to mines, railways and navigation, to military art, to fine arts, to electro-chemistry and chemical arts, to the production and transmission of motive power, the mechanical arts, to surgery and medicine, to horology, to astronomy, to meteorology, to geodesy, to agriculture, to apparatus for registering, and to domestic uses. It is expected that the exhibition will prove much more attractive to Americans than that at Paris.