SCIENCE OF THE DAY.

New Zealand Herald, Volume LXVII, Issue 20722, 15 November 1930, Page 5 (Supplement)

SCIENCE OF THE DAY.

LOOKING THROUGH STEEL. Radium's gamma rav, much the same sort of ray that gave the world radio and artificial sun tan, is now able to look through steel girders and battleship hulls with all the case of a small boy gaping through a stereoscope.. Engineers can now put a photographic plate behind the si eel gil ders of a skyscraper and see that they have developed no flaw. Mechanics can lake pictures of locomotive wheels and determine if all is well within. litters can stmlv vital points of a submarine for suspected weakness. The discovery is the work of 3Vlr. Robert F. Mehl, superintendent of tho division of physical metallurgy in the American Naval Research Laboratory at Washington.

Hitherto the. X-ray has been the solo means of such inspection for defects in metals, and there have been three notable disadvantages which the gamma ray has overcome. The X-ray, for example, with equipment generally available, cannot penetrate deeper than 3;in. to <lin. within reasonable time. Research experts and a largo electrical company have estimated that it would cost £20,000 to develop an X. ray machine capable of penetrating the lOin. reached by the radium gamma ray. Another advantage of the new method is portability. The radium and tube necessary could be carried in a special small brief case for use iti Alaska or remotest Africa, in contrast ( o the bulky equipment needed for X-ray, and the added requirement of a plant to develop high electric current. Finally, there is the matter of simplicity. The technician can group the objects he wants to photograph, and leave word for the nightwatchman to drop tho radium into the tube when lie starts work. The ray will operate during the night, and the technician can pick up his plates in the mornin P- . .

An important phase of (he new discovery is its sensitivity. It will reveal defects as minute as two per cent, of the metal's thickness. '1 he extent of (lie practical application is stili problematical. Early indications are that it will lie of great value in testing heavy castings. Naval experts are interested in its possible use for testing heavy-guns and metal gun turrets.

A MARVELLOUS WATCH. Ail astronomical watch, (ho gem of 'he Packard collection, now in the Smithsonian Institution in the United States, strikes t lie hour and minutes, and has a perpetual calendar and a miniature skv in which 500 stars appear in true relation with one another—concealed machinery keeping tlieni in their correct positions each hour of the night. The watch shows the time of sunrise and sunset, and has a separate minute hajid which shows the difference Between the regular time of day and the tune as it appears on a sundial. THOUGHT REGISTERING MACHINE. A machine which is alleged to register thought by curves has been invented by Professor Ilans Berger, of the. University of Jena, Germany. The invention converts thought into electric energy, which is registered on a chart. T.he thought chart" looks like a weather or earthquake chart. Deep thinking shows violent ups and downs; shallow thinking merely a zig-zag line. So far, however, nobody lias been able to read the thoughts themselves, and further research will bo made to discover whether an interpretation of the curve is possible. HEARING WITH FINGER TIPS. During his researches on the possibility of hearing sounds with the finger tips, Professor It. H. Gnult, of North-Western University. United States, discovered that while the human ear is from ten to six times better than a finger-tip in distinguishing between the pitch of a tone, it is no better at all in tolling how loud or soft a tone is. In his earlier work he perfected, in collaboration with the Bell Telephone laboratories, a special type of telephone receiver, by means of which a deaf person could " hear by pressing his fingers against (he vibrating diaphragm. In this way the sense that would carry the vibration of the brain would he the sense of touch rather than the sense of hearing proper. REMARKABLE FOOD PLANT. A food plant growing wild in quantity in the desert hills of south-eastern California, where rainfall is as little as two to six inches a year, has been discovered by plant scientists of the American Department of Agriculture. The plant, known as Ammobroma, or sand-root, had not been seen by white man before 1928, according to information. Mr. Frank A. Thackerv and Mr. French Oilman, of the department, at that time found it growing on an area of about 200 square miles on the cast side of the Colorado desert in south-eastern California, and on an equal area in Soriora, Mexico. They learned that from time immemorial the Papago Indians had been eating it either fresh or dried.