SCIENTIFIC MISCELLANY.

Otago Witness, Issue 3714, 19 May 1925, Page 67

SCIENTIFIC MISCELLANY.

(For the Witness.) THE TINIEST BEETLES. Specimens of two specie* of beetles smaller than ajiy hitherto known have been collected, with larvai supposed to be their young, from a common fungus— Polyporus—on a fir near Mexico City. They are about one-fiitieth of an nch long and a-iifth as wide. A SOUND RADIATING MATERIAL THAT IMPROVES. Celeron is a compound of fibre and bakelite, and in its mixture with ’xon filings for telephone diaphragms, phonograph records, and radio loud-speakers 't is said to give results much more delicate than those obtained with metal. It is found in the mixture to have Uie peculiar property of improving with age. MYOPIA FROM CITY LIFE. The disorders brought by city life in elude near-sightedness, according to a lecture by Sir Arthur Keith to the British Optical Association. All children are oom with eyes adapted to distant vision, but of 1000 British children 10 or more lose the power of seeing distant objects clearly by the end of the fourth year, and 150 are myopic by the age of 20. The causes seem to affect only the growing eye, myopia being one of the disorders ot growth. The healthy eye seems to withstand unchanged all strains, however, and it is concluded that the eyes to be favoured are those unsound at first. NEW ELEMENTS OF ARABLE EARTH. Evidence that nickel and cobalt are generally present in soils has been ob lained by two French analysts," Bertrand and Mokragnatz, from examination of 33 samples from France, Germany, Denmark, Italy, and Roumania. The amounts in k paits per million of earth ranged between P 8.6 aiid 4.7 for nickel, and 11.7 and 0.3 for cobalt. It is suggested that dust of these two metals may reach arable soils from interplanetary space. NEW ALUMINIUM WELDING. Tlie welding of aluminium is accomplished in a new German process in much the same way that lead is soldered, the difference consisting in the use of a special solvent for dissolving the oxide. When the oryacetylene flame supplies the heat a mixture of 60 parts of potassium chloride, 12 of sodium chloride, and tour of potassium sulphate has been found satisfactory, but with a less intense heat a little more potassium sulphate is required to lower the melting point. Applied in powder or as a watery paste this mixture melts just before the aluminium itself. A SELF-ADJUSTING WATER-WHEEL. The floating water-wheel of Mader Van Niekirk, Cape Province engineer, is designed to adjust itself automatically to the varying height of the propelling stream. As first, constructed, the wheel has eight V-shaped paddles about 13ft long and 14in wide, and it is so mounted'oil an airtight tank that it rises and falls with Hhe river’s changes through any height up to 36ft. It is used for pumping irrigating water from a distance of 28Uft to a height of 40ft above the source. Philip and gearing are placed on the river bank, and the wlieel and tank are connected by a shaft having universal couplings at each end. The two 6in cylinders can be regulated in stroke from 2£in to lOin, 25 strokes per minute being obtainable with water flowing three miles an hour. THE HAZARDS OF MINING. Coal mines rarely contain poisonous dusts, reports R. K. Sayres, of the U.S. Bureau of Mines; but in other mines dust from the more soluble ores of such metals as lead, mercury, and arsenic often produces bad poisoning. The dust from the rrore insoluble 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 dust, and “siderosis” when caused by iron dust. Dust may also predispose to bronchitis and other respiratory disease. The principal coal mine hazards in the United States are due to abnormal air conditions, such as the presence 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. Some disorders of foreign mines are of little importance in America—nystagmus appearing to be nonexistent, probably on account of superior lighting, and affections of knee, hand, and elbow, Sbeming to be known only in very limited areas. A METEORITE OF PLANETARY SIZE Mining for platinum promises to reveal the secret of the world’s greatest meteorite. Meteor Crater, at Canyon Diablo Arizona, 4200 ft in diameter and 570 ft deep to the visible N floor, has long been supposed to be tttb scar made by the fall of a great mass Irom apace, ami the Indians have a legend of a visit from a god ..f heaven whose fiery chariot lighted the sky and quickly disappeared into the earth. Numerous fragments of meteoric iron have been found in the vicinity. Much fruitless search for the buried portion has been madp, and at last an exploratory boring under the i-touthern wall of the crater lias reached much oxidised meteoric iron M n depth of 1346 ft. After penetrating 30ft into this material the tools jammed, preventing further progress. The 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 crMo from the north at an angle of about 45 degrees, leaving a scattered trail of the fragments found. As some of these contain platinum, mining for this metal is to be undertaken. The buried mass is believed to he of asteroid size, weighing a thousand million tons, although most other meteorites knov« n hf ve ranged between a few grains and a h\v hundred pounds, with a very small rumber leaching weights estimated in tin. LIVE INSECTS IN THE MUSEUM. A museum feature that is not fixed, but is changing constantly or often, is the novel exhibit of the American Museum of Natural History showing a diversity of insects in a living condition. Within the limits of a case of a few square feet, it is noted, may bo seen a range of animal habit as great as that represented in vertebrate menageries by the flesh-eating tiger and tho herbivorous elephant, and a range of structure comparable to that of the water-inhabiting fish and the arboreal monkey. Utetnesia bella, one of the most beautiful of the moths, has developed from caterpillar to adult in this menagerie of insects. The drug-store beetle, sitrodrepa panicea, feeds without apparent injury on the poisons of tue pharmacy, but is hero seen living m a diet of com meal. Such disrenutab.a insects as the cockroach and the bedbug are given a place. Among the water insects are the Belostomidea, some of whim attack a good-sized fish; the water-stridcrs, that skate on ponds and streams; the water scorpions, that breathe through their “tail”; and aquatic lame of the dragon-fly and damsel-fly. One of the most interesting of the insects :s the grass-green praying muntis. A picturesque common posture of this creature is of waiting like a statue with trap-like front legs raised, not in prayer but m readiness to grasp any insect victim that may approach.