Science Siftings

New Zealand Tablet, 18 April 1912, Page 59

Science Siftings

By 'Volt.'-

Smallest of Screws.

. The smallest, screws in the world are made in a watch factory. • They are cut from a steel wire by a machine, but as the chips fall : from the ) knife it : ; seems as though the operator were simply cutting up the wire for his own amusement. No screws can be seen, and yet a screw is made at every third - operation. The fourth jewel screw is next to invisible, and to the naked eye it looks like a grain of dust. With a magnifying glass, however, it is seen to be a screw with 260 threads to the inch, and with a very fine glass the threads may be seen quite clearly. These little screws are four onethousandths of an inch in diameter; It is estimated that an ordinary thimble would hold 100,000 of them. About a million are made in a month, but no attempt is ever made ; to count them". In determining the number, 100 of: them are placed on a very delicate, balance, and the number of the whole amount calculated from the weight. ~ All the ; small parts of the watch are counted in this o way, probably 50 out of the 120. After being cut the screws are hardened and put in frames, about 100 to 1 : the frame, heads up. This is done very rapidly, but "entirely, by the sense of touch instead of by sight, so that a blind man could do it as well as; the owner of the sharpest eye. The heads are then polished in an automatic machine, 10,000 at a time. : The plate on which they are polished is covered with oil and a grinding. compound, and on this the machine moves them very rapidly by a reversing motion until the polish is perfect. : r , , ; , . - . Aerial Flights. .•.-.- • '""' :> ';\ ■[■'."-- :- ; ' \ A cable message states ; that the Daily Mail is attacking the Government - for neglecting aeroplanes. It says that Britain has only six officers flying regularly, and only one thoroughly up-to-date aeroplane, as compared with 500 aviators in France and hundreds in Germany. The strength of the nations' aerial fleets at the end of 1911 was as follows: 9 steering balloons, 192 aeroplanes; Germany, 17 and 16 England, 4 and 21; Austria, 2 and 4; Kussia, 3 and 8 • Italy, 3 and 14; United States, 8 and 52. -Germany alone . has a greater number of dirigible balloons than of aeroplanes, its balloons numbering nearly twice that of France. France has 21 times as many aeroplanes as steerables, and its aeroplanes are twelve times as many as Germany's. .England's aeroplanes are five in excess of Germany's, and those of the -United States are four timesjthe number in. Germany. Experiments in Germany (remarks the Freeman's Journal) show that infantry fire, even of gatling. guns, is insufficient against a balloon. ■* A hole of two-fifths of an inch causes a loss of only eight pints of gas per second, which is infinitesimal, 'and the ; small hole caused by a rifle bullet appears to close of itself under the} pressure of the gas. Experiments on captive balloons show that after 7600 shots had been fired in seven minutes" the balloon showed no apparent loss of; floating power. ;A 1 hole of four inches,, caused by a cannon-ball, appears necessary to cause a balloon to descend; but even then its descent is not rapid, and artillery fire is considered impossible against aerial fleets. . It is believed that a war between two powerful nations will begin with a battle in the air. 1- The flying machine y that will rise higher than its adversary has an easy victory. It may drop combustibles on a f balloon, or, flying above an aeroplane, will so disturb the air that the:machine will lose its equilibrium and drop instantly* to the ground..