SCIENCE SIFTINGS

New Zealand Tablet, 3 October 1918, Page 46

SCIENCE SIFTINGS

By “Volt.”

A Tip for Soldiers. Do you know that your watch is a compass, or, at an / I r a ’ te > 3,8 good as one, if you only know how to use it ? If you do not, learn now.’ You want to find the north? Well, point the hour-hand to the sun, and the south is exactly halfway between the hour-hand and the figure XII. on the dial. For instance, suppose it is four o’clock. Point the hand indicating that hour to the sun, and halfway between it and the figure XII. is the figure 11. That will be opposite to the south. Just the same, if it is eight o’clock, the figure X. is the south. Look to the north and your right hand is the east, your left the west. Very simple, is it not? But, like all simple things, how many know it? Those Wonderful Propellers. A modern aeroplane propeller is one of the strongest and most perfect products of man’s handicraft. Some aeroplane engines run at 1700 revolutions a minute, and can be geared up to 2000. An engine of this power would use a Oft Gin propeller, and the speed of the blade-ends would be in the neighborhood of 600 miles an hour. Revolving at this terrific rate, the slightest imperfection in the wood from which the Propellers are made would tend to disrupt them and cause them to fly to pieces. For this reason only the best and hardest wood from the heart of the tree is used for propeller blades. It takes 2000 ft of timber in the rough to furnish 200 ft of wood good enough for propellers. Black walnut is the very best kind of wood lor propeller blades, for besides being intensely tough it does not splinter when hit by a projectile. Next, in the order named, come mahogany, white oak, ash, maple, birch, and cherry. The Healing Sun. It has always been understood, although more or less vaguely, that sunlight is efficacious in the treatment of many physical ills ; but it is only of late years that the knowledge has been reduced to definite scientific form. Experiments with cases of bone tuberculosis by French and German physicians have been so successful that sanatoria have been established exclusively for the application of the sunlight treatment. One of the most famous of them is in the Alpine village of Leysin, which stands forty-five hundred feet above sea level. There hundreds of tuberculous people, especially those suffering from bone, or surgical, tuberculosis, are treated, with most gratifying results. In the hospitals the galleries that communicate with the wards all face south. Patients are wheeled out into the open sunlight, to which the feet and legs are first exposed. As they become used to the treatment the r .st of the body is exposed. So accustomed do the patients become both to the sun and to the low temperature that the children play in the snow almost naked, and their skins become so bronzed that it would be impossible to tell from their looks to what nationality they belong.