SCIENCE NOTES.

Otago Daily Times, Issue 14383, 28 November 1908, Page 10

SCIENCE NOTES.

— The glass tubes formed by lightning striking in "sand—half an inch or moro in diameter and sometimes 27ft long-havo just l>een feebly imitated by powerful electric currents discharged through powdered glass. Compared with Nature's product, iho tiny pipes, of darning-ncedlo sizo and less than an inch long, suggest tho tremendous energy of lightning. — It is stated in the recent report : of the Astronomer-Royal that tho past year has been signalised by the discovery of a new satellite of Jupiter, ■ very faint, and very distant from its primary.. The discovery was the result of close scrutiny of the 'series of photographs of Jupiter's sixth and seventh satellites, which have,, been taJvori 'at eachopposition since their discovery, at the Lack Observatory in-1805. ' ' ■ — Experiments by marine engineers all over the world have now demonstrated the fact that the depth to which tho wan disturbance of tho surface of the sea exteh'W averages 15ft. A homely pr»of of thi»'» to be found in the way in which a diver can work on the bed of the ocean- without fooling the slightest jeffect. from any motion of the'waves over his head. —An asbestos- shingle roof, when properly made, will outlast tho life of .the building itself (says Popular Mechanical. The simple exposure to the elements causes the cement covering of tho asbestos fibre to crystallise, and it becomes more and more serviceable as time rolls on, steadily toughening and hardening with, exposure. Tho fact that the elements take' bettor care of ,thcse shingles than the best paint or dressing does away with , this expense. ■:..••••.'■ — The .lower atmosphere and the upper atmosphere- are believed by Professor 'J. Hann to be two very different gaseous mixtures. At the earth's surface the composition is-Nitrogen, 78.03; oxygen, 20.99; argon, 0.94; carbonic acid, 0.03; hydrogen, 0.01;" neon, 0.0015; helium, 0;00015; krykton, 0.00010.:.- At•■ a height; Of 20 kilometres (12.43 miles) he finds the nitrogen increased to 84.34- per cent., with 15.19'0f oxygen. At 100 kilometres the hydrogen seems increased to .99.45 per cent., with 0.453 of helium and only 0.099 of nitrogen., — "■There-is no reason, save ignorance, why shipwrecked sailors should die in their open, boats of starvation." , Tho speaker was a botanist (says the New .Orleans Times-Democrat). "Let the' shipwrecked include a.light' net in their.luggage," ho' said, "and let them trail this net behind them as they sail or row upon the 6ea's surface. : Every few hours they can haul in and take from it a meal of small shellfish or other ;tiny, sea fruit. Everywhere the sea's surface teems '.with animal and vegetable matter capabjo. of sustaining life." ;.' '■'•■' — Mosquitoes being oho "of the pesfsof many countries, Mr Maxwell Lcfroy, of the Indian Entomological/Department, has made a special study of 'their destruction, and has been particularly successful with a novel method of trapping them. Ho uses a box about a foot square, which has a, hinged lid with a small aporturo that can be closed by a slide. This box has,a bottom of tin, and -the sides arc lined with baize. Set In a dark corner of .tin) room, tho simple'apparatus proves an Attractive retreat for the insects seeking;to hido from the sunlight 1 on entering iho house in the morning. They' soon collcot inside, and when all have settled, 1 a teaspoonful of benzine is poured in, and the lid is closed. The prisoners aro quickly suffocated. In 31 davs he destroyed over 3100. j- ;'• ' ' " — The_ fragility of incandescent gas mantles is asorious drawback to their use, but a moro durablo fabric seems to have resulted at last from the experiments of German chemists. The mantles now so familiar have a tissuo of cotton,or ramie, on which oxides of thorium and ocriuir have been precipitated. Attempts to'use• other natural fibres have failed,-and success-, ful new material is an artificial ailk made by dissolving cellulose in ammoniate of copper. This silk mantle takes up thorium nitrate,* which ammonia charges in the fibre to hydroxide of thorium. The thorium silk docs not absorb moisture, like, the old mantles, and it has many times as great assistance to shock. ..•.■■: -' — Computations of to-day ',- havo , shown that Groat Britain has "in sight," so, tf speak—although'it is all below the ground —an available coal deposit of nearly 145,000,000,000 tons. At the rate of production and consumption prevailing, -the supply w«wld last about' 900 years. The coal measures of Lancashire aro 9000 ft ia thickness. Moreover, there arc many countries which possess coal deposits that; have never been touched. Besides the great coal fjolds of Europe and America, as now worked, ■. thore are undoubtedly coal deposits in China, in the in Australia, in South America, in. Britisli North America, in Alaska, in ; the Indian archipelago, and elsewhere. • — A eeries of: interesting .tests, designed to show the great reduction in the number of microbes floating about in the atmosphere after city streets havo. been cleaned, has been conducted in a foreign city.' Sensitised plates were held, exposed above the streets for 15 minutes, and then were prepared and .their contents examined.. Plates exposed over an uncleaned street showed so many colonies of various types of germs that it was impossible to count them. Following a superficial cleaning' of the street three plates showed /respectively 800, 900, and 1000 colonies. When tho street had been cleaned by a squeegco machine ,tho plates showed only 135, 140, and 150 colonies. It was announced after those tests that prizes to be given to tihtf.' streetcleaners, drivers, and foremen who show the cleanest streets during tho rest of the year. ', — Professor Darwin has declared his belief that the age .of the earth .cannot be less than one hundred millions'of'vcars. M. Flammarion tells us now that this estimate is too low by at )ca9t fifty millions of years. The late Lord Kelvin declared soon before his death that his former estimate— 10,000,000 years—was far too low,, and that the more he studied Iho question the moro j .strongly inclined he was to accept the estimate of Professor Darwin. Finally Professor Fournier feels convinced that Iho eventual estimate which shall be proved to 1)6 scicntifieially accurate will show that the earth must lx> at jeast as old as the son of the great Darwin declares it jo he. The proof which has upset the common Biblical affirmation of 6000 .years as being the ago of (ho earth is found, beyond the possibility of controversy, in the examination of geological strata. Tho great geologist Lyall was the first io apply the pcirio (stone) te6t, and his experiments demonstrated beyond cavil that the lime which must have elapsed between the beginning of the cooling process of tho fragment of tho sun which wo now inhabit and the formation of the outer strata must have , been at least several millions of years. , Modern criteria have changed all calculations which were made previously to tlw ■new declarations, made by Darwin and Harkness, the age of petric strata being now quite as easily and as accurately determinable as the ago of trees, or a« the age of disinterred human bones.—Popular | Science Sittings...