Science Siftings

New Zealand Tablet, 10 November 1910, Page 1859

Science Siftings

BY ‘VOLT’

A Cargo Hard to Handle. Asphalt is said to be the most difficult cargo for a vessel to unload. The asphalt is taken out of the asphalt lakes in Trinidad in a semi-fluid state, and by the time the vessel reaches a northern port has hardened, so that to unload it it is necessary for the men to go into the hold and dig it out with pick and shovel. This takes time, and a vessel carrying such cargo always has to arrange for a considerable stay in port. Colored Underwear for Summer. Colored underwear for hot, sunny climates is advocated in a leading editorial by American Medicine (New York). When it was first suggested (says this paper) that skins were pigmented to exclude too much light, physicians were sceptical, preferring to consider nature a fool to create colored races in light countries. The light theory was utterly rejected by the French and British, however, who are now taking steps in the tropics to give themselves the same protection by colored underclothing that nature gives to the natives by colored skins. Ten Miles of Panama Canal Finished. According to the Isthmian Canal records a stretch of five and a half miles of the Panama Canal at the Atlantic entrance was opened to navigation on August 13 for the sand and sand rock fleet of the Atlantic division. Tugs with barges in tow from the quarry and crusher at Port Belle and from the sandpits at Nombre de Dios which now enter the French canal at Cristobal will hereafter enter the canal off Hindi, and from that point continue as heretofore through the old channel to Gatun. Five miles of the canal at the Pacific entrance is in use by vessels of all kinds, and the five and a half miles at the Atlantic entrance now to be used for construction purposes will make ten and a half miles already actually useful. Lighthouse Voices. Wonderful possibilities are claimed for a Swedish invention called the photographoue, by means of which it is said that sound waves can be registered on a sensitised plate. The negative is developed in the ordinary way, and the sound curves transferred to ebony plates, from which the sound is reproduced as by the gramophone. The photographone records can be reproduced ad infinitum, and if the original music or song should not be strong enough to fill a large concert hall, the sound can be increased as desired. On account of the immense volume

of its sound, the inventor prophesies that the photographone will replace fog sirens in lighthouses. Instead of the inarticulate howl which the sirens send out in the night, the photographonic foghorn will call out the name of the lighthouse for miles over the ocean.

Ingenious Arc Lamp Pole-topi

When arc lamps are supported directly over the tops of poles by fixtures known in practice as pole-tops, it is customary for the trimmer to climb either the pole itself or a ladder leaned against the same when he goes to recarbon the lamp. This is objectionable not only because of the danger in windy weather, but also because a man steadying himself on a pole or ladder cannot use his hands to the best advantage". To overcome these drawbacks an ingenious type of pole-top is being introduced in England, in which the lamp is hung from an inverted stirrup pivoted within the pole-top proper. Paying out a wire rope (which runs down one side of the pole) allows the stirrup to swing the lamp several feet out from the pole, and to then lower the lamp so that it can be trimmed by a man standing on the ground. On lowering the lamp it is automatically disconnected from the circuit, but is switched into it amain when the lamp is returned to its normal position by pulling the rope taut.

Sound Waves and Rain Drops.

From a series of observations made during thunder storms, W. J. Laine, of the Finnish Society of Sciences, shows in an interesting way that sound waves in the atmosphere affect the size and form of raindrops. He notices that a peal of thunder invariably causes a rainbow to take up a peculiar vibration and to widen in appearance, its red end becoming almost invisible while the violet is greatly intensified. A little later the colors which the shock has obscured narrow down and are more brilliant than before. First the yellow reappears, and then a band of striking red. Assuming as true Pertner’s Rainbow Theory, which attributes rainbow colors to the mixture of the intensities of different light waves, caused by the diffraction of light by the raindrops, Mr. Laine concludes that this illusion of a vibrating rainbow is due to a rapid alteration of the diameter of the raindrops and the consequent variation of the distance between maxima and minima of the diffracted light waves. Furthermore, he holds this phenomenon to be due to the sound waves of thunder, and not to lightning, since the interval between the lightning and the thunder is often as much as twenty seconds.