Science Siftings

New Zealand Tablet, 22 November 1906, Page 35

Science Siftings

By «Volt»

• ■" r Indestructible Glass. In consequence of • many recent inquiries, the U.S. "Can- ■ sul at .Liege: -has' sent to Washington a report about - the hardened glass and crystalware manufactured' in Belgium. -On account : of the costliness of, the process, . but few articles are as yet made of this glass, .'" which is called agatine. It serves well for dishes and ;^ tumblers. An agatine tumbler may be dropped on a hard floor or thrown across a room with but slight ' chance of breaking. With great" violence, of course, the glass can be broken,,, but- its , power of resistance is described as astonishing. , __/ A New Style of Nail. - - A recent patent is designed to help the novice at carpenter work to drive a nail straight when it is necessary to" fasten abutting pieces of wood .together - in the manner technically known as. toe-nailing-: In this operation it is necessary to drive the -nail at such an angle that it will enter the second board against which the first one abuts,. so that the two will ' Be held together.' The difficulty in the. use of - the or- --„ dinary nail for this purpose, is to drive it at justthe right angle, so that it will take a proper hold of both pieces. With the new nail this is accomplished by making use of a peculiar plough-shaped end, which causes the nail to describe an arc as it passes < through the wood. A New .Method of Heating. A Frenchman has invented fabrics called thermoph--ile fabrics, which are in reality electrical heaters. Heat of a mild, temperature is produced by a combin-' at ion .of a textile and a conductive thread. Electrothermic wires are hidden -in the fabrics. No smoke or gas is thrown off in the heating., process and, this . makes the fabrics very " hygienic and suitable for sick- . room heating. Many other uses have been found for the fabrics, notably in electrically-operated railways, - - and electromobiles in which ' thermophile carpets, either alone or in connection with a heating plate, are used to advantage for providing a most comfortable heating effect to the passengers. Unhealthy Trades. The latest' compilations. which have been made show that the air in cutlery factories, is laden with invisible metal dust, and this, being carried into the lungs, causes asthma and _ consumption. The steel grinders, bending over their work, inhale such huge quantities/ of metal dust that they rarely live -beyond the age of forty. All metal trades are - very hazardous, and phthisis or tubercular - affections and respiratory diseases are the penalties of these pursuits. The rate, of mortality among- brewers is 50 per cent, greater than that .among men of ordinary callings. . Gout is an enemy which makes itself sorely felt in this occupation. Bakers, too, are more than normally subject to j premature death. In the flour there -is a very small - microbe which has its effect on the teeth and attacks the drums of the cars, causing deafness. The Shape of the Earth. ' It was almost to be expected (writes H. P. Hollu in the • English . Mechanic ') that . the 'statement, that the earth is .shaped like a pear, would lead to some misconception. One correspondent seems to think it- is - definitely proved that our -earth is not a true oblate-, spheroid— so much so that the dissymmetry is -easilymeasurable, and that the stock end of the pear is' at;.. the South Pole. The pear shape is simply a. sugges-' tion from theory, and that actual measurement, on. which all knowledge depends, gives only the slightest indication of departure " from the traditional ' orangeform. AH that geodesy has done is to give a hin(t-/_ that the Equator may not be a circle, but the ellip—^ticity is so small that it would not cause a .differ- "~ ence of a mile between "the lengths of the greatest / and least radii. This.., is evidently a different , kind of fruit to. the ono some r readers suppose. There is as much variety of shape among pears as there is of color among plums. . .