SCIENCE AND INVENTIONS.

New Zealand Herald, Volume L, Issue 15411, 20 September 1913, Page 4 (Supplement)

SCIENCE AND INVENTIONS.

SPEED OP HERTZIAN WAVES. Thb speed of Hertzian -waves has been made the subject of experiments between Toulon and Paris by'MM. Abraham and Dufour and Major Ferrier, and the results, which have been communicated to the Academic des Sciences, show the speed to be 295,900' kilometres a„second. It is noted that this result,' which is described, as only approximate, approaches very nearly to the speed of light—299,ooo kilometres per second. It is suggested that further experiments may prove the speed of both kinds of waves to be identical. STEEL AND RUBBER MOTOR TYRE. One of the newest ideas in motor tyres is to have treads imbedded wife % number of parallel strips of spirally-woven steel fabric running around the circumference. The effect is some 90,000 upstanding spirals of steel wire interlaced with the rubber. The combining of steel, and rubber in such a way is expected to- secure increased durability and produce a tread which is proof against surface cuts and punctures. .It is also claimed that the steel spirals assist the escape of heat from the tyres and thus tend to keep temperature. BALL-BEARING CARRIAGES. Some account of the tests of ball-bearings on railway carriages that are being made in Sweden has been given in a Consular report. For 18 months such bearings have been kept in regular service by the Karl-stad-Munkfors Railway on a bogie-truck passenger carriage pulled by a benzineelectric motor, and it is estimated that operating cost has been reduced 7 per cent. There has been also a saying in lubrication and,other costs. A passenger bogie-truck carriage has been fitted with ball-bearings, by the Swedish State railways, running on express service between Stockholm and Goteborg, This company is to try more carriages, giving them a most thorough test. SEARCHLIGHTS IN SHELLS. An illuminating projectile recently perfected by the Krupp company in Germany is designed to replace searchlights in military operations, as searchlights offer good tar**** for the enemy and are often destroyed This, projectile contains a. number of tubular bodies composed of illuminating substances. These are set on fire by the explosion of the projectile, and, through the unfolding of a small parachute that forms part oi each illuminating body, float in the air for a short time above the area to be illumin- l The projectile is exploded by means U a timing mechanism, while a spring forces the parachute out of the tube of the illuminating body as soon as it is released from the projectile. ORIGIN OF PEARLS. Many theories have been put forward ; to explain the origin of pearls, .beginning ! with the pretty legend of the Arabs and Hindoos to the effect that pearls are dewdrops fallen in the sea and received by the oyster, but it has been established ; that the origin of a pearl is a dead parasite round which the oyster deposit* a [ secretion in a series of spherical envelopes. The parasite has been identified and has I a strange history. If it lives and dies in the oyster and is coated with pearlmatter, it becomes a jewel. If, on the other hand, the oyster is scooped from its shell by a hungry fish the parasite remains in the stomach of this fish and developes into another stage of life, where it stays and dies unless its host becomes in turn the prey of another species of fish in whose belly the parasitic Jonah again suffers a sea change into something less rich than a pearl, but strange enough, for it becomes ■ft definite little sea creature, living its own life.. and no longer parasitic. Only one oyster in 30 or 40 contains pearls. But it is on record that an oyster taken in the Indian Ocean held good pearls, and fiom the famous Ceylon fishery came a shell with 67. The finest pearls are the pure white. But nowadays the fashion is for pearls tinged with rose. Black pearls come from Mexico and from Tahiti Garnet red pearls are highly prized among Hindoos and Jews. From the Bahamas come rose-red pearls, pale with delicate wavy lines. Pale blue pearls are often found in edible mussels and violet in the ark shell. There is a big shell in the West Indies that contains very beautiful rose-red pearl, but as they have no layer i of pearl matter they cannot be considered true pearls. At first they are magnificent, but gradually they lose their colour and fade. With fine skin and good lustre or orient black pearls and the deep shades of red, yellow, etc., are as costly and as highly-prized as the purest white. The loveliest single large pearl is said to be in a museum in Moscow. It is known as "La Pellegrina,'' and is an Indian pearl, perfectly spherical in shape, pure white is colour, and almost transparent. It weighs 28 carats. AVIATORS AND FIRE. Fire on an aeroplane in flight is (writes Mr. Charles C. Turner), like practically every other aviation danger, preventable, and it is amazing that with relative safety within grasp the majority of flyers continue to run unnecessary risks. The one cause of accidents that cannot be stopped h the failure of the pilot to do the right thing or to take reasonable care. It should be impossible for a machine to burst into flames after landing; but this is a terrible danger in the case of bad landing causing the tanks to break, and it can only be guarded against with practical certainty at present— until solid petrol is carried instead of liquid— the pilot cutting off the ignition before reaching ground. Many terrible accidents have been, due to omission to do this by pilots suffering from loss of nerve, or "having their minds entirely taken up with the effort to avoid a smash. The writer questions I whether at the average flight school pupils are sufficiently drilled in one or two essential points of this kind. They are warned, of course, but the lesson is not forced home so as to become second nature. If it be ever feasible to carry solid fuel, the [ fire caused by a bad smash would presumably be a small affair, and there would be time to extricate the pilot and save him and the machine. Meantime, such preventives as are available should be made compulse*/, so that the careless designer and manufacturer and the foolish pilot could be saved from themselves. One of the chief causes of fire is the back-fire due to the improper closing of the inlet valve. This is clearly to be avoided in the majority of cases by examination of the engine, and it is one of the things that show how very important is intimate knowledge of his motor to the aviator. It was the breaking of an inlet valve that caused Mr. Pizey's machine to catch fire recently, and incidentally afforded us an example of splendid presence of mind which should show all aviators that even in the worst predicaments there may be hope, and that the fight must be kept up to the last tenth s>i a second. Mr. Pizey skilfully brought the aeroplane down, and he and his passenger just had time to jump out of the burning machine. Well, even knowledge of the 'engine will not tell a pilot that an inlet valve is likely to break ; and clearly it is up to the enginemakers to render 'such a mishap impossible. But here, too, the use of solid fuel would enormously lighten the consequences. In an ordinarily bad landing, aad even during flight, the leaking and breaking of petrol tanks and pipes constitute so terrible a danger - that the present writer is ever wondering why there are not more disasters. It is the sort of thing one suffers nightmare over, and no one who has flown and has the smallest spark of imagination can fail to have many anxious moments thinking about it. Makers certainly are putting stouter material and better fittings in their work than in the very early days, but a great deal remains to be done; and the writer would like to see every machine in use put back into the workshop and rendered less a death-trap in this respect than it is. In a great many cases stronger tanks ought to be used, whilst the use of armoured petrol-proof rubber tubing ought to be made compulsory^