M. K. C., Park, Col.—The air-tube of an argand-burner lamp should always be open, as its use is to supply air to the inside of the wick while other air is being furnished upon the outside. If the wick be turned too high the oil will rise in it by the principle of capillary attraction (not siphon) too rapidly to be properly consumed. Some of this oil passes off as unconsumed carbon, and some may drip, in its original form. 2. The amount of carbon in the atmosphere varies with local circumstances, such as population, rainfall, sewerage, etc., from 2 to 10 in 10,000 volumes of air. The oxygen and nitrogen of the atmosphere are invariable in their proportional parts: twenty-three parts (by weight) of oxygen and seventy-seven of nitrogen.
Lile E. Argile, Kilbourne City, Wis.—The final cause of the war of 1812 was the search of American vessels by the English, and the impressment of United States sailors into the service of Great Britain. All of this trouble, however, probably grew out of the ill-feeling that had existed between the two nations since the Revolutionary war. The cause of the Mexican war was the annexation of Texas to the United States.
R. L. Stevensun, Quincy, Minn.—Half-morocco binding consists of a fine quality of cloth covers with morocco corners and morocco spring back. Library binding is all leather.
P. S. Williams, Fort Lyon, Mo.—The largest ship in the world is the Great Eastern, described on page 63 of Our Curiosity Shop for 1880. Length, 680 feet; breadth, 118 feet; height to top of bulwarks, 70 feet.
E. E., Stralm, Iowa.—The first watch was made by Peter Hele, a clockmaker of Nuremberg, Germany, in the year 1477.