Nature Study for Grammar Grades Author:Wilbur Samuel Jackman Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: III. METEOROLOGY. A. Manual Training. Apparatus-making. 1. The Hygrometer. Select two mercurial thermometers which under similar conditions read the sam... more »e. Fasten these, side by side, on a small board to the bottom of which (about two and one-half inches below the bulbs) is attached a shelf sufficiently large to support a wide-mouthed two-ounce bottle. Wrap one of the bulbs with clean, thin muslin and allow a bundle of twenty-five threads to reach from the muslin envelope down to the bottom of the bottle. Fill the bottle with clean water and allow the threads to enter through a hole in the cork. The water evaporating from the muslin cools the bulb. The dryer the air at a given temperature, the greater the amount of evaporation and the more the bulb is cooled, consequently the lower the reading of the wet-bulb thermometer. 2. Thermometer. Must be purchased. 3. Barometer. Should be purchased. The tube, if great economy is necessary, may be purchased and filled carefully with mercury. This may be fastened to a yard or meter stick to show the height of the mercurial column. 4. Raingauge A three-inch standard gauge may be purchased for one dollar and twenty-five cents. (Henry J. Green, manufacturer of meteorological instruments, 1191 Bedford avenue, Brooklyn, N. Y.) The U. S. standard gauge is accurately made as follows: (a) Cylindrical tube 20 inches long, inside diameter, 2.53 inches. (b) Cylindrical receiver, inside diameter 8 inches, with funnel shaped bottom. The sides of the cylindrical part of (b) may be about 2 inches. (c) The receiver (b) is fitted on the under side, or funnel end, with a sleeve or short tube which slides over the tube (a), so that all the rain falling into (b) will pass down into (a). (d) The depth of water falling int...« less