Science Siftings

New Zealand Tablet, 8 April 1915, Page 55

Science Siftings

By 'Volt.'

*| Talking Across the Country. -/ ; : - '. i| To keep nearly thirty thousand electrical waves a minute in perfect order; on a telephone wire is one of the detailed problems that the American Telephone and Telegraph Company had to solve in establishing the long distance telephone connection between New York and San Francisco, opened by the talk between Mayor Mitchell of New York and Mayor Rolph of San Francisco. Some of the waves have one shape, some another (said General Manager Hiss). They are as different from each other as the waves of the sea. It is not the problem of defending one simple current, but as many as one hundred and twenty thousand a minute. All these minute currents, millions and millions required for a conversation, must be carried electrically over the line to San Francisco and then converted back again to sound waves, which agitate the air of the room and affect the ear as air waves. Building a Zeppelin. The building of a Zeppelin is not the work of a day. The mere work on a machine takes an entire year, and when that work is done another three months must be spent in testing. Stretched in a framework of girders, there are from seventeen to twenty-five balloonettes from end to end. Over these and over the girders is an outer skin of proofed canvas. Slung under the great length is a series of cabins. Eight in front is the station of the look-out man, who is in charge of the starting and the landing: he has anchors siung beneath him. In the first boat, which is entirely covered in, are two petrol engines. Behind this boat is the gangway, fitted up with sleeping berths 'for the crew. In the centre is the observation station. Tt is from here that the bombs arc dropped, and it is in here that, the marvellous steering and "sighting apparatus is installed, as well as the wireless plant. Luxurious Military Aeroplanes. The German arrow type of flying machine can compare with nothing so much as an automobile de luxe (says a writers in T.l'.'s .Journal of the War). It has the strength, the perfection, the reliability, the safety of a superb motor car. And it has the luxury. On the dash-board before the pilot, in addition to his control gears, there is a nest of drawers containing, amongst other things, a Thermos flash, chocolate cubes wrapped against the damp in tin-foil, a small bottle of brandy in case the aviator should become faint, a petrol sponge, for wiping the goggles, a revolver holder, a despatchcase with sharpened pencils of different colors, so that the dispositions of the enemy's troops can be more adequately marked, a map board, and maps. Moreover, the exhaust pipe of the engine passes under the floor boards, so that the pilot, who must constantly keep his feet at an angle on the pedals, may have them warmed throughout the flight. The flyer, too, sits in a. comfortably upholstered club-chair. Room-paper and Light. Some papers absorb a great deal more light than others, and therefore necessitate more gas and electricity. For example, white absorbs only thirty percent, of- the light rays, while deep chocolate absorbs ninety-six per cent. Thus a room papered in deep chocolate would require nearly eight times as many windows and lamps to make it as light as an exactly similar room papered in white. An illuminating laboratory recently made an exhaustive test of the various wall papers commonly used in order to determine their light-absorbing qualities. This test showed the percentage of light absorbed by each color to be as follows:—White, thirty; chrome yellow, thirty-eight; orange, fifty; plain deal, fifty-five; yellow, sixty ; light pink, sixty-four; emerald green, eighty-two; dark brown, eighty-seven vermilion, blue-green, and cobalt blue, eighty-eight, and deep chocolate, ninety'

These'figures^ show that if a room papered with dark green be; repapered with chrome yellow it will be five times as light with the same lamps and windows. In many cases house-holders pay too much for electricity and gas-lighting because their light-absorbing - wall coverings destroy the light rays. J . ■ ' --