A temperature of -60 to -80° F. is not dangerous to human beings who are properly clothed, if the air is still, while 30 or 40° higher, if accompanied by a gale of wind would kill every living thing before it. Very low temperatures almost invariably coincide with perfect atmospheric quiet.
Tubing of copper, one inch inside diameter of standard thickness, will stand a heat of 700° F.
Lake Bonneville in Utah, of Pleistocene age, twice filled a basin which is now a desert. The lake at one time covered an area of 20,000 square miles, and was 1000 feet deep.
Before the days of coined money the Greeks used copper nails a scurrency.
The latest development of the mercury tube is the use in connection with constant current transformers and series arc lamps. With this combination it is possible to get a direct current for the arc lamps and yet have an alternating current source. The direct current arc lamp is much better than the alternating current lamp, as it gives a much steadier lamp, and is free from the humming which is always present in the alternating current lamp. A number of these outfits have been installed, and are giving very good satisfaction.
Julius Caeser was the first man to engrave his own image on a coin.
The shadings of all colors begin with white and end with black. White may, therefore, be considered as the color from which all other colors emanate and black as the one in which all others disappear.
Homer mentions brass money as in use 1184 B. C. among the Greeks.
Oil may be prevented from entering the boiler with the water condensed from steam by putting an upward extension on the pipe leading to the boiler, and providing it with a means of tapping off the oil that will rise in the pipe above the horizontal pipe connecting with the boiler.
When anthracite coal is used in boilers, it is necessary to employ wide grates of large area and a comparatively low firebox. When consuming bituminous coal, narrower grates of smaller area and a high fire-box are necessary.