Science Siftings

New Zealand Tablet, 18 March 1915, Page 49

Science Siftings

By ‘ Volt.’

Providing Against Overhead Attacks. The next design for United States field artillery guns will be provided with a split-rail gun carriage, which will permit the elevation of field artillery guns to almost any angle. The Army Ordnance Department is developing projectiles which will leave a trail of smoke by day and of light by night. * It is believed that with such projectiles the range upon aeroplanes can be found, and an effective defence provided against an attack from overhead. Tram Cars and Rubber Tires. In order to reduce the noise of street cars, and particularly the flat-wheel nuisance, it was suggested at a recent meeting of the Tramways Association, in Newcastle, England, that street cars be provided with tires of rubber. It was argued that the wear on the rails would be much reduced, and the life of the rubber tire would exceed that on motor trucks and ’buses, which are credited with an average life of 20,000 miles. It was also argued that a higher rate of speed would be possible with the flexible tire. The Limit of Eire Control. At the United States army proving grounds at Sandy Hook all records with 12-inch guns were broken when a range of 20,000 yards, or over 11 miles, was attained with 700-pound projectiles. This is the weight of shell used in the 12-inch mortars. Eleven miles is the limit of fire control, since it is not believed that any range finder can be developed which will make the fire of guns effective beyond this distance, the curvature of (he earth rendering it impossible for range finders to locate an object at a greater distance. Announcing the Correct Time. Correct time is announced every even hour in the port of Lisbon, Portugal, by means of two lanterns placed on iron columns 100 feet high. The lanterns each have three faces, measuring 6.5 by 8 feet. At exactly five minutes before the hour a horizontal line of light appears on each face, and on the tick of the hour this light is extinguished. The signals may be seen even in the daytime at a distance of a mile and a-half. At night the position of the lanterns is indicated bv rec red lights. The signals are worked electrically under the control of a clock in the Astronomical Observatory of Lisbon. The World’s Telephones. On January 1, 1914, there were 13,700,000 telephones in the world, and 32,900,000 miles of telephone wire. The United States, with 9,000,000 stations, owned 66 per cent, of the total number in the world ; while Europe, with less than 4,000,000, owned about 27 per cent. When we consider that the population of the United States is but 6 per cent, of the world’s population, and less than 25 per cent, of that of Europe, the large proportion of telephone stations makes a remarkable showing. New York City alone has more telephones than Belgium, Hungary, Italy, Netherlands, Norway, and Switzerland combined ; there are more telephones in Chicago than in the whole of France, and more in Philadelphia than in the whole of Austria.