Science Sittings

New Zealand Tablet, 8 July 1909, Page 33

Science Sittings

BY • VOLT

Nailmaking. A common nail is an excellent illustration of the difference between old and new methods. Formerly the metal was cut into strips and then forged into shape with hammers, and an expert took about one and a half minutes for each nail. To-day they are made of steel and are lighter and stronger. Strips are cut with steam shears and fed into automatic nail machines. One man tends three machines, each machine dropping a nail every second. Thunder's Rumbling. In accounting for the rumbling or rolling of thunder, ' which has heretofore been explained by the echo theory, it is now stated that a flash of lightning is made up of innumerable smaller flashes, which go to make up the. whole. The rolling thunder is due to the primary sounds of successive discharges or flashes. When we see a relatively prolonged lightning flash we witness in reality a number of discontinuous discharges following down the same path, and the sounds of these successive explosions come to us like the rattle of a rapid fire gun. This .continuity is quite different from oscillation. Watches for the Blind. On the face of one of the latest watches designed for the use of blind people the hours are indicated by movable buttons in relief on the dial. A strong pointer shows the minutes. The blind person passes his fingers over the dial, the button indicating the hour he finds to be depressed, while he position of the hand gives the minutes. The buttons are held, by a circular plate beneath the dial, which has at one point on its circumference a notch into which the buttons drop, one after the other, as the plate revolves wih the movement of the works. This plate serves instead of the ordinary hour hand of a watch. Abysses of Ocean. More than half the surface of the globe is hidden under water two miles deep. Seven million square miles lie at a depth of 18,000 feet or more. Many places haze been found five miles and more in depth. The greatest depth yet sounded is 31,200 feet, near the island of Guam. If Mount Everest, the world's highest mountain, were plucked from its seat and dropped into this spot the waves would still roll 2000 feet above its crest. Into this terrific abyss the waters press down with a force of more than 10,000 pounds to the square inch. The staunchest ship ever built would be crumpled under this awful pressure like an eggshell under a steam roller. A pine beam fifteen feet long which held^ open the mouth of a trawl used in making a cast at a depth of more than 18,000 feet was crushed -flat as if it had been passed between rollers. Morse's Invention. The Morse telegraph invention lingered for five years in the hands of its starving inventor because capitalists were indiffetent or incapable of appreciating its merits. It was several years before Congress voted an appropriaion to allow its inventor to make a practical test of and burlesque bills were offered to provide means for communicating with the man in the moon. ' He's a very good, but shiftless painter, if he would only stick to his job,' some one said of Morse. 'The idea of telling by a little streak of lightning what a body is saying at the other end of a wire ! ' His instrument, it was said, was all very well .as a mantel ornament or for a mistress to call her maid, but the wires couldn't cross rivers, oceans, and deserts. Even after the line was up between Washington and Baltimore and Silas Wright sent a despatch to the Democratic Convention at Baltimore declining its nomination" 1 of him to the vice-presidency, it was not accepted as true until a committee went to Washington.