SCIENCE SIFTINGS

New Zealand Tablet, 25 November 1920, Page 46

SCIENCE SIFTINGS

(By “Volt.”)

For Better Weather Forecasts. A new solar watch tower is being built by the Smithsonian Institute in the Hala Mountains in the Arizona (G .S.A.) desert from which great things are expected. In this region the sun shines from a cloudless sky almost every day in the year so that daily observations may be made of the amount of solar radiation. This information will make it possible to forecast tire weather and the temperature more accurately than ever before. The same institution has for some time maintained a similar station at Calarna, hili, where conditions are especially favorable lor such observations. The Weather Bureau of Argentine lias received daily telegraphic reports from the Chili station and as a result has enjoyed remarkably accurate weather forecasts, as well as advance information as to the amount of rainfall. By combining the observations made in Chili and Arizona the weather prophet expects to greatly increase the accuracy of his forecasts. The Hand Grenade. I he hand grenade is by no means a modern invention; in fact, the French used it as early as 1594, naming it after the pomegranate because of its resemblance to the fruit. After a long period of disuse it made a. reappearance during the siege of Port Arthur. Since then there have been many developments, and the grenade as used to-day is of very complicated and delicate mechanism. The Americans have paid particular attention to it — their patents office has considered no fewer than 300 designs. At the beginning of the great war the Russians used crudely-made grenades that cost little over a shilling apiece. But the casualty lists of the users being nearly equal to the enemy’s it was not a popular weapon, and was soon dropped. 1 he grenade used by the British is known as the Mills pattern. ft is operated by a timing device set for five seconds. After being thrown it works in this way: A lever is automatically ejected, letting go the strikingpin, which releases and fires the cap igniting the fuse. I his burns for five seconds and ignites the detonator, which explodes the charge' of powdered ammonal. The fragments of the grenade, numbering about 60, scatter in all directions, and are effective within a radius of 100 feet. • he shell of the grenade is of cast iron, and is lacquered on the outside with a solution of gum shellac and methylated spirit to prevent rust. A Chinese Secret. Aon have noticed, on an old plate, the network of cracks in its surface. They, are there because the glaze has cracked, and can be seen because the dirt has worked into the earthenware through the cracks. You also know that the colored pattern on some kinds of pottery wears off after a time, while-that on other kinds, especially on some porcelain, will remain there for over. Why is this? There is a kind of pottery and metalwork made in China and Japan which, for permanency and beauty surpasses anything European manufacturers have ever been able to produce. It is commonly known as Chinese and Japanese enamel-ware. The Chinese have known how to make it for about 2,000 years; wo do not know how to do it to-day. Such consummate skill is required, and the ingredients of the pigments used have been so well guarded, that although we know the process we have been unable to duplicate the work.