SCIENCE NOTES.

Digger (Invercargill RSA), Issue 5, 16 April 1920, Page 15

SCIENCE NOTES.

MACHINES CONTROLLED BY SOUND The control of electrical machinery ny sound, and even by inaudible vibrations, is claimed by an Austraiian aviator. In his late demonstration, a small model moior-car was fitted with the essential batteries, without wires or ordinary wireless apparatus, and by the blowing o! a whistle the car was startcd, direeted to the right cr left, and stopped. Control was practicable up to a distance of a mile. The inventor has given attention also to other machines, and is said to have had suecessful results in the control of air-planes and torpedoes. . , A SPIRAL BELT PUMP. A novel pnmp has recently rnade its appearance. It consists simply of a spiral spring belt, a grooved weight which 'turns with the bottom loop of the belt and holds the latter in place and a driving crank and pulley for turning the belt. Despits this simple construction ihe pump is capable of lifting a thousand gallons of water per honr from a depth cf 300 feet even worked only by liand according to reports. The coil-like cable is sunk to any depth by ihe rotating weight. Obeying the law of capillary attraction, the water lodges between the turns of the spiral spring and only falls out when it reaches the top of the pump. A. TWELVE-MILE SHAFT. At the meeting of the British Association in 1904, Mr (now Sir) Charles Parsons discussed at some length the feasibility of sinking a shaft to a depth of twelve miles in the earth ; about ten times the depth of any shaft in existence. He concluded that the work couid be accomplished in 85 years at a cost of £5,000,000. Subsequently exhaustive experiments to determine whether rock-pressure at so great a depth would crush the shaft in and destroy it proved that the construction of even deeper shafts was practicable; viz., 15 miies in limestone and 30 miles in granite. The cost of a shaft 12 miles deep, at present-day prices, would not be much mere than the cost of one day of.the recent war to Great Britain alone.

WASHING CARPETS ELECTRICALLY A newly-developed electrical carpet washer makes possible the washing of carpets without taking them off the fioor. No water touches the rug or carpet. Instead. a warm "sudsy" cleaning compound is scrubbed down to the bottom of the nap so as to clean every fibre thoroughly and take out all dirt or grit. Two brushes, rnade of sofe, yielding rubber, are oscillaled by an electrie motor 500 times a minute, thus, the maker declares duplicating the scrubbing motion of the human hand. The soap compound w'nieh is uscd by the carpet washer is said to ■contain no harmful cliemicals or animal fat-s.

REBUILDING FRANCE WITH TANKS After having established itself as one" of the most destructive weapohs of the recent war, the tank, in various modified forms, is now building up another reputation as one of the greatest tooLs in the hands of the reconstructors of devastated Europe. Credit in generous measure is due the British authorities for their ingenious application of the erstwhile military tank to a large number of distinctly peacetime tasks. Thus the British have modified their small and large tanks for service as tractors for road work, agricultural purposes and can-al-boat towing. More recently they have equipped some of their largest tanks witli powertul derricks and clam-shell buckets for the purpose of aiding in the work of clearing the ruins of devasted France and Belgium. This machine has remarkable facilities for operating 011 any kind of clearing the ruins of devas-tated France ' it may be. A HARD SUBSTANCE.

If aluniinium oxide be vitrified at a temperature below its temperature of fusion, a product of great density and hardness is obtained possessslng properties peculiarly favourable to the manufacture of many tools. This process is now employed ed for the production of "drawing-stones" for the purpose of the'finest metal wire drawing. The degree of hardness of this suhstance resembles that of sapphire and it exhibits uncommonly little sign of wear and tear after use.