Indiana and Ohio supply a whetstone made from a sandstone of a coarser grain than the novaculite of Arkansas, but nevertheless quite uniform. It may be used with either oil or water, and is useful for sharpening household cutlery, penknives, or ordinary carpenters’ tools. But since it is easily cut and grooved by hard and sharp steel, the fine instruments of dentists and surgeons should not be edged or pointed on this stone.
Scythe stones and mowing machine stones are practically all made from mica-schist rock found in New Hampshire and Vermont. These rocks are generally of a dark-gray color, and composed of very thin sheets of mica and quartz crystals interlaminated.
A simple experiment made about fifteen years ago led to the discovery of carborundum and crystolon. By heating a mixture of salt, sand, and sawdust, and powdered coke in an electric furnace, the variegated colored crystals of carborundum and crystolon were produced.
These crystals are extremely hard, cutting glass easily, and, in fact, almost any substance except the diamond.
Emery cloth and paper are very well-known commodities, but are little used to-day because the artificial abrasives are just as effective and cheaper. Experiments to obtain an artificial product having the main characteristics of emery resulted in the making of alundom and aloxite, both of which are shown in the museum series.
High and Low California.
California, with an area of 158,000 square miles, is the second largest State in the Union. It exhibits wide geographic diversity, for it includes the lowest area in the United States—Death Valley, 276 feet below sea level—and the highest—Mount Whitney, 14,501 feet above the sea.
Similarly there is a great diversity in scenic effects, climate, and vegetation. Records obtained at meteorologic stations in the Salton Sink indicate a maximum temperature of 130 degrees in the shade, the highest recorded within the continental United States, while it is probable that minimum temperature on the higher peaks, like Mount Whitney and Mount Shasta, approach the minimum within our boundaries, a total difference of nearly 200 degrees.
Records of rainfall in the most arid sections of the southern deserts of the State represent the extreme of aridity in the United States, showing an annual average of less than three inches and periods of twelve months or more, with only traces of rain, whereas the precipitation in northwestern California is very heavy, an annual average of close to one hundred inches being recorded at a few stations in Mendocino and Del Norte Counties.