SCIENCE NOTES.

New Zealand Herald, Volume LXIII, Issue 19298, 10 April 1926, Page 4 (Supplement)

SCIENCE NOTES.

EXPLORING TEE SKY WINDS OF HIGH ALTITUDES INGENIOUS READING METHODS. ♦ The behaviour of the air at great altv tudes is dealt with in the report of tlio International Commission for Mie Exploration of the Upper Air, just issued by the Meteorological Office of the Air Ministry. Sir Napier Shaw is president, of the commission, and its results are expected to bo of great value aeronautically. The speed, direction and variability of the high-altitude winds will affect greatly the operation of the long-distance air expresses of the future if, as is quite probable, they fly high on their voyages from continent to continent. An exact knowledge of the upper air currents will bo essential to the pilots in order that they may obtain the highest possible speed from the minimum expenditure of fuel. Besides this, the effect of density on aircraft and aero-engine performance is a matter which has an important bearing on service aircraft and engine design. The readings are obtained by various ingenious methods. The sounding balloon, the artificial cloud, the kite, the kite balloon, and the aeroplane are all used in the work of exploration. Clockwork meteorographs and meteorographs in which a small airscrew, turned by tiie passing air, rotates the cylinder are employed as recording instruments for the balloons. THE TREE OF DEATH. Jew's Ear, as the name of a ftinguS, is a corruption of Judas' ear, given to it because the fungus referred to is often found on the elder, on which tree Judas is supposed to have hanged himself. It is curious that-on. account of this connection with Judas the fungus should have "become a famous medicine in quinsies,

sore thrbats, and strangulation ever since." Why the elder should have heen selected as a gallows for the traitor I Apostle is, considering the usual size of j the tree, puzzling enough, says a Writer in the Chemist and Druggist, hut Sir John Mnundeville, or the romancer who wrote under that name, states that when he was nt Jerusalem the very tree 011 which the hanging took place was still in existence near the pool of Siloam. — / SETTING OF CEMENT. An Investigation Report of the United States llureau of Mines on Calcium Sulphate lietardei'3 for Portland Cement, compiled by Mr. E. E. Berger, shows that it is evident that the important problem of the reaction of cement with calcium sulphate is not yet considered to be solved. Something has been achieved, however, by this investigation. Mere analysis of the clinker cannot decide what amount of calcium sulphate should bo used in order to retard the setting of the cement; tho properties of tho clinker and its mode of manufacture have to be studied. Plaster of Paris seems to be the best retarder when used in a proportion giving ! a maximum of S'o3 of 2 per cent. Gypsum as such must he added in larger proportions and may fail to act; when is ground up with the clinker in the tube mill, however, it is partly converted into plaster of Paris. Anhydrite alone diii not give a satisfactory cement with any of the clinkers tried; it retarded only clinkers which wero by themselves slowsetting. Mixed retarders, consisting of mixtures of either anhydrite or gypsum with plaster of Paris, produced satisfactory cements provided they contained enough SO3 as plaster of Paris to retard the clinker. ,