Science Siftings

New Zealand Tablet, Volume LII, Issue 40, 21 October 1925, Page 62

Science Siftings

(By Volt)

Photographing Sounds. / Sound photographs recording the noises in the cabins of Imperial Airways cross-Chan-nel passenger aeroplanes whilst in actual flight are to be obtained by Professor A. M. Low with a view to locating the actual source of the various sounds. The big Napier engines used on many of the air expresses have already been silenced to a remarkable degree, but it is found that the propeller revolving at high speed and the vibration of the stay wires produce distinct noises, and it is with a view to tracing and eliminating these that Professor Low is to carry, out his experiments. , , , It is hoped to produce a passenger air, express in which the noise inside the cabin is actually less than on the latest express train. •' . , The Ninth Wave. The many thousands who will spend some time by the sea during the summer months will have an opportunity, if they 1 care to take it, of investigating for themselves the reliability of the notion that the ninth wave is always the biggest, Tennyson wrote:- — And then the two Dropt, to the cove, and watch’d the great sea fall, Wave after wave, each mightier than the' last,. Till last, a ninth one, gathering half the deep And full of voices, slowly rose and plunged Roaring. . There can be no doubt that a belief prevails that the waves breaking on the beach keep increasing in regular series till the maximum arrives, and then the series begins again. The fact seems to be that when two waves reinforce each other a big one results, but this does not seem to occur at fixed intervals, and those who prophesy that such and such a wave will reach farther than its predeces- 1 sors, during the rise of the tide, will prove wrong' three times out of four. Cool Air and Sunshine. Professor Leonard Hill lias been telling the International Congress of Radiology how health and the clothes we wear are related. Referring to the habit of wearing far too many clothes, he pointed out that garments except thin zephyr or open mesh material screened off the ultra-violet rays from the body.' Artificial silk was more permeable than natural silk; in fact, a zephyr of artificial bilk was the least obstructive of almost any material, but even this prevented fifty per cent, of the ultra-violet rays from reaching the skin. ■ . The body ought not to be exposed long to the action of the sun’s rays, and exposure should always take place in cool conditions. Hot sun boxes and sunlight treatment under glass in hothouses were wrong. People should nob be overheated, and exhausted, but : stimulated and made happy by cool • air and sunshine.' ,