MODERN SCIENCE.

New Zealand Herald, Volume LXII, Issue 19031, 30 May 1925, Page 7 (Supplement)

MODERN SCIENCE.

ITEMS OF INTEREST,, /AGE OF THE EARTH. ESTIMATES BY SCIENTISTS. Many attempts have been made- to determine the age of the earth. Edmund Halley, tho astronomer, endeavoured to calculate tho age from o orations of tho amount of'salt at intervals of one or two centuries;. Professor Jojy recently' estimated the ago of tho earth to be 80,000,000 to D 0,000,000 years, from tho quantity of sodium in the sea, judged by the rate at which the rivers pour saline waters into tho oceans to be slowly concentrated during tho ages. Tho temperature of tho earth increases toward tho centre, and from the temperature gradient Lord Kelvin calculated that about 100,000,000 years ago the earth was a molten mass. Geological and biological requirements seem to indicate that this estimate is too low. Sir Ernest Rutherford has estimated that a mineral known to be very old bad existed years. Professor Joly is responsible for another recent method .—one which depends on the fact that colour changes are brought about in minerals by radio-active substances. Microscopic haloes are to be seen surrounding minute f articles of uranium and thorium. Proessof Joly has estimated tho age of tho haloes in Irish mica to be from 200,000,000 to 400,000.000 years. THE GREATEST METEORITE. Mining for platinum promises to reveal tho secret of the world's greatest meteorite. Meteor Crater, at Canyon Diablo, Arizona, 4200 ft. in diameter and 570 ft. deep to/ tho visible floor, has long been supposed to be the scar mado by the fail of a great mass* from space, and the Indians have a legend of a visit from a god of heaven whose fiery chariot lighted the fiky and quickly disappeared into tho earth. Numerous fragments of meteoric iron have been found in tho vicinity. Much fruitless search for the buried portion has been made, and at last an exploratory boring under tho southern wall of tlio crater has reached much oxidised meteoric iron at a depth of 1346 ft. After penetrating 30lt. into this material the tools jammed, preventing further " progress. Tho point of boring was suggested a number of years ago by D. M. Barringer, Philadelphia, mining engineer, and his view is that the main meteorite came v ' from tho north at an anglo of about 45 , degrees, t leaving a scattered trail of the '. fragments found. As some of these contain platinum, mining for this metal is to bo undertaken. Tho buried mass is believed to be asteroid size, weighing a thousand million tons, although most other meteorlites known have ranged between a few grains and a few hundred pounds, with a very small number reaching weights estimated in tons. SELF-ADJUSTING WATER-WHEEL. l'he floating water-wheel of Mader Van Niekirk, a Capo Province engineer, is designed to adjust, itself automatically _to tnc varying height- of tho propelling 1 stream. As first constructed, the wheel has eight V-shaped paddles about 13ft. long and 14in. wide, and it is so mounted on an air-tight tank that it rises and fulls with the river's changes through any height up to 36ft. It is used for pump- . ing irrigating water from a distance of > 280 ft. to a height of 40ft. above the source. Pump and gearing are placed on the river bank, and the wheel and tank aro connected by a shaft having universal couplings at each end. Tho two 6in. cylinders can be regulated in stroke from 2£in.. to 10in., 25 strokes per minute being obtainable with water flowing three miles an hour. THE HAZARDS OF MINING. Coalmines rarely contain poisonous dusts, reports Mr. R. It. Sayres. of the American Bureau of Mines; but in other mines'dust from the moro soluble ores •of such metals as lead, mercury, and arsenic often produces bad poisoning. The dust from tho more inpolublo ores—such as galena or lead sulphide—does not often give harmful results. Dusts that irritate the lungs frequently give rise to "pneumoconiosis," a disease that is known as "silicosis" when due to .breathing fine silica or rock dust, "anthracosis" (or miner's phthisis or asthma) when resulting from coal dnst, and "siderosis" when caused by iron dust. Dnst may also prodispose to bronchitis and other respiratory disease. Tho principal coalmine hazards . in tho United States aro due to abnormal air conditions, such as the of carbon monoxide, hydrogen, sulphide, and increased carbon dioxide, oxygen deficiency, high ' temperatures, and humidities, and possibly to breathing dusts. Hazards from impure drinking water and unsafe sewage are also to be considered. WAR ON PARASITES. In an address at the London Y.M.C.A., Mr. /'A. E. Moore Hogarth, director of the Collego of Pestology, recently asserted that the elimination of tho ectoparasite is a definite branch of modern protective medicine. He explained that his council wero convinced that disease was transmitted by tho "creepy-crawly" things that, when they hud the chance, feasted on human bodies. Tho council were now actively engaged in preliminary step's, having for their object the opening of tho pestology clinic in the east end of London. BATTERY CHARGING AT HOME. The widespread adoption of "listen-ing-in" sets nar> led to an enormous increase in Britain in the demand for lowvoltage batteries. These are mostly of the accumulator type, which has _to be charged at intervals. Small batteries are also largely used in cars for ignition, lighting and starting. Charging from lighting circuits at 220 volts is very wasteful, because between 95 and 98 per cent, of the pressure is converted into - heat—and is therefore wasted—in the resistance necessarily involved. Electric supply undertakings and some garages havo special appliances for charging such batteries without incurring this loss, but accumulators are heavy articles to take to and from the nearest charging station, which may bo a long distance away. A device for charging low-voltage accumulators from house-lighting circuits has been 'invented by Mr. F. A. Wilkinson, M.i.E.E. This consists of a changeover switch, placed on the negative main circuit next to tho consumer's fuse. By means of this switch the current can bo passed through the battery to be charged instead of direct to tho out-going terminal. When damps aro lit and current is flowing tho battery is automatically charged. NEW AEROPLANE ENGINE. A French engineer, M. Louis Damblanc, has invented an aero engine in which is embodied an automatic mechanical device enabling high speeds to bo maintained at any elevation. Tho ordinary type of engine loses half its efficiency at about 16,500 feet, owing to the rarity of tho atmosphere at that height. 'J ho engine, if fitted with M Damblanc s device, loses very little, under theCte conditions. The device, which includes an automatic stabiliser, occupies very small space and weighs a little over four pounds. RED LIGHT AND THE MICROBE. How useful microbes can bo made to work at,double speed by means of light was' told recently at- tho Royal Institution by Mr. Thorno Baker, who said ho bad discovered that alcohol for motor fuel can be produced, by, fermentation far . more rapidly if-tho-vessel containing tho microbes is flooded with red light. Other micrpbes which, when grown in the ordinary - way, are of a bright orange Colour become green if grown in green light, and white if cultivated in blue light. Tho effect of coloured light on microbes may be of great value some time hence, when.tho world is dependent on ui.m -in ad o raw mat er iaU.