SCIENTIFIC AND USEFUL.

New Zealand Graphic, Volume IX, Issue 17, 23 April 1892, Page 426

SCIENTIFIC AND USEFUL.

SAWDUST. It is stated that a German firm has perfected a means of making a profitable disposition of sawdust by which it is applied to a mechanical use, and has thus far been attended with success. An acid is mixed with the sawdust, and the whole mass moulded into blocks or any other form, resulting in a fine material for building purposes. The blocks assume extreme hardness of surface, and are practically non-combustible. The material in the moulded forms is said to be much stronger than timber in these forms, and much lighter than either iron or steel, and can be prepaied cheaply. electric search lights. The subject of the use of electric search lights in military operations at night continues to engage the attention of different Governments, and experiments have recently been conducted both in Spain and in Turkey. In the former country a Mangin projector was employed. It was mounted upon a special waggon, together with a length of cable and accessories, whilst on a second waggon the boiler and a turbo electric generator giving 110 amperes at 70 volts were placed. In Turkey two projectors were tested, one being of the same type as that used in Spain, and the other a German apparatus with a parabolic reflector. The results of the experiments were entirely satisfactory, and it was found possible to distinguish objects at distances ranging from three to nearly six miles. AMMONIA FOR SNAKE-BITE. Dr. Gunther, F.R.S., the celebrated herpetologist, recommends the following treatment for snake-bite: A ligature or two should be made, as tight as possible, at a short distance from the wound, and between it and the heart. The ligature should be left on until the proper means are provided to destroy the virus in the wound, and until medicine is taken internally ; or until great pain or swelling necessitates its removal. The punctures are to be enlarged by incisions at least as deep as the wounds, to cause free efflux of the poisoned blood, and to facilitate its removal by sucking. The wounds should be sucked by the patient himself, or by another person whose mouth is free from wounds. THE SPREAD OF DISEASE BY BOOKS. Seldom do we stop to think, on taking a book from a public library, who might have handled the volume last. Books are lent out and go from family to family, no attention being paid to the fact that they may have been handled by a patient having a contagious disease. The British Medical Journal mentions a case where a physician recognised in the house of a patient suffering from scarlet fever a book which be had noticed a few days before in the room of a former patient suffering with the same disease. On inquiring he learned that a few days after borrowing the book the symptoms of the second case appeared. The paper used for covering library books soon becomes roughened and undoubtedly furnishes the means of transmitting infectious diseases. Libraries should be notified either by the Board of Health or by the attending physician of any cases of infectious diseases. DISCOVERED. Diamonds in their rough state are not much more attractive than pieces of quartz or glass, and one picked up in the diamond fields of South Africa would probably be thrown away as a worthless specimen of stone by a boy or girl. In fact, something like this first led to the discovery of the rich diamond mines near Cape Town, South Africa. A Dutch settler’s child was found playing with pretty pebbles one day near her fathei’s lonely home in South Africa, when a stranger happened to pass. Noticing the glassy pebbles carefully, he induced the child to give the playthings to him, and, after an examination, he was satisfied they were real gems. History does not tell whether he made the child a present for the valuable discovery, but the incident led to an exploration of the country, and to the establishment of the largest diamond mining industry in the world. MECHANICAL FLIGHT. Mechanical flight is a subject often discussed by schemers, but now for the first time approached in a truly scientific manner. Lord Raleigh and Professor Langley, both physicists of considerable standing, have investigated the conditions necessary for successful mechanical flight, and in their experiments they have employed a kite 110 feet in length and 40 in breadth, which has been propelled by means of a light petroleum engine, working a large screw. The result of this experiment must not be put down as more than affording a promising field for future study. In these trials it has been found quite possible to drive the large kite carrying an engine worked mechanically, and to cause it to lift itself by compression of the air beneath it. CURVATURE OF THE EARTH. Any figures relating to the earth’s curvature must of course be understood to apply to large surfaces of water, the unequalities of the land preventing exact measurements. A straight line a mile long, touching the earth at its middle point, would be 2 04 inches from the surface at each end. The visible horizon of a man sft. 6in. high, standing on the shore, would be two miles 1537 yards distant. Such a person could see a rock rising 12 feet out of water 5 miles 1,320 yards away. If he stood 20 feet above sea level, the same rock would be visible at a distance of 9 miles 120 yards. To find the distance of the horizon :1| times the square root of the height of the eye in feet equals the distance of the horizon in miles nearly. Given the distance of an object, the height the eye required to see it may be found by squaring the distance in miles and multiplying by s for height in feet.