SCIENCE SIFTING.

Auckland Star, Volume XLIII, Issue 215, 7 September 1912, Page 15

SCIENCE SIFTING.

SUN RAYS AFFECT -'WIRELESS." Wireless telegraphy, we pre often Tβ- | minded, can be carried on muefh better Iby night than by day, and the view that ! the sun's rays interfere was confirmed during <th<? recent solar eclipse. Tests during the passing o f the shadow over the sun were made between the wireless stations of the Royal Dockyard at Copenhagen and the Blaavandshuk station on the coast of Jutland. The messages sent gradually increased in reliability and clearness, and became more distinct just after the culmination of the eclipse.

FOSSIL CAMELS. The first fossil camels ever found intact in America are being set up in the Carnegie Museum in Pittsburgh, and curious little animal,s they are, being not much larger than greyhounds, with slender legs and long necks. These skeletons were clothed with flesh ages ago, and existed in the Niobrara Valley, in Western Nebraska, where ProL O. A. Peterson, of the Carnegie Museum, and Dr. F. B. Loorais, of Yale University, found them. These fossil camels are said to be the remote ancestors of the modern camels ajid dromedaries of Arabia and Africa, and of the American llamas.

WHY MOVING PICTURES MAKE WHEELS TURK BACKWARD. Every one must have noticed that in moving pictures the wheels of carriages or automobiles often seem to be turning backward instead of forward. An autfhority says:—ln taking a. moving picture there are, perhaps, sixteen exposures made each second. If now the spokes of the wheel of a carriage move with a speed so that the spokes are in t ! he same position at each exposure, that wheel will seem to stand still in the picture. If the wheel is moving slower, then the spokes will be seen further backward in the successive views, and the wheel will seem to turn backward, while it will be seen to turn forward when the spokee move fast enough to occupy positions further forward in each exposure. It is a matter of the interruption for the exposure and the motion of the wheelIf there arc sixteen exposures and the wheel turns through the space between two spojkes in one-sixteenth irf a second, the wheel would be in the same position ait each successive exposure, and 'so would not ecem to move at all.

ODD FACTS ABOUT SLEEP. All the organs of life rest in some wa; or other. The heart has an .interval of rest between each combined act of contraction and expansion and the beginning of a fresh act. Between each expiration of the lungs and <bhe succeeding inspiration there is a period of repose. Physiologists have calculated that the heart reposes during about one-fourth of the time. Certain of the other organs suspend •■-heir activity in part dnring sleep. Old physiologists supposed that sleep -was caused by the pressure of the blood on the brain- But modern physiology, with a tendency to regard the brain as the origin of all force and of all functions of fche body, inclines to the view that sleep is caused hy a withdrawal of blood from the brain. A curious trait has marked men of large train—that of sleeping at will. Bonaparte used to throw himself on -the ground and go to sleep within a space of two minute*. Pitt was a sound sleeper, and sJept night after night in the House of Commons ■while his colleagues watched the debate and roused him -when it was neceeaary that he should speak.'

WHAT DISLODGES SEA WALLS ? The dislodging by wave action of large stones or masonry blocks from the face of break-waters or sea walls has been investigated by the engineering department of University College, Dundee. Such blocks weighing several tons have been forced out, even under heavy overlying courses, and it has been explained that the effect might be due to hydrostatic pressure, exerted upward and outward above the line of wave impact, or ito a compression of air entrapped in openings struck by the water. In the experiment made, it was assumed that ■ the striking wave ha-s a maximum velocity of 80 feet per second. It was found <tha,t this would give a maximum internal hydrostatic pressure—like that of a hydrostatic press —of about 2.9 tons per square foot; and that it might cause a pressure from the enclosed air of about 6 tons per square foot. The experiments i proved, however, that a vastly greater force might 'be present —that of waterhammer action, eueh as is sometimes i noticed, when the flow of water through '■ a long pipe is suddenly stopped at the ■ open end. This would occur under > special conditions only, but it was shown i that tthe impact upon an open joint of a i wave of the stated velocity might set up a water-hammer action of 40 tons per square foot, or even more. It was suggested that walls exposed to w-avea ! should have drains or openings on the ' .inner side to prevent excessive water, a/ir, or water-hammer compression.

A LESSON PROM THE PAST. It is humiliating to be toW by the editor of the "Scientific American" that tihe Great Eastern, built in 1858, "was a safer vessel than the Ti-taniic, ibuilt only the other day. The Great Eastern, he maintains, -would probably have survived the accident that sent the Titanic to the 'bottom. She was 'built by Brunei, " proMa'bly tihe moat »He and versatile engineer the world has ever known." He set out -with a free hand to build a safe ship, and he sulSSeeded so well that the Greait Eastern survived contact wiith a submerged rook <ttn.t (tore a hole BOft long iby J Oft wide in her outer skin. The Titanic had only a single skin above her double bottom, bat the Great Eastern Wad a double skin, carried up to a point well above the wateriine. Brunei 'built his ship so that there was a hull witnan a hull, and a space of 3ft •'between, so that if the outer skin was torn, -waiter would not enter the vital part of the ship. But ■realising -tlitait a blow might rupture both skins, he subdivided the ship into 51 separate compartments, with strong ■budlMieads between there reaching to ! tihe bop dock. On 'the Titanic the (birlk- ; heads ran only from side to side, a.nd were not carried high up; but in the Great Eastern there "were also .bulkheads running .the length of the vessel. " Such was the ship of the 'fifties, a eanelyI designed, enormously strong, and pre--1 eminently safe vessel. Ooetfly she was, and financially a failure; 'but her failure was not due to the expense of the admirable construction, but rather to the 1 fact that she was greatly in advance of ! her time. It was not possible to secure the full! cargoes or passenger .lists that i were necessary to render so huge a ves'sd profitable." The writer declares 1 the Titanic, with (her single skin, 16 I water-tight compartments, no longitudij nal divisions, and tow 'bulkheads, to have I ■been in every point -of comparison, aa regards safety, distinctly inferior to the [Great Eaatena.