=Rainfall.=——Under the general term _rainfall_, meteorologists include, besides _rain_ itself, _snow_, _hail_, _sleet_, etc. The term _precipitation_ is also often used. Rainfall stands in close relation to human life and occupations. It feeds lakes and rivers, thus furnishing means of transportation, power for running mills and factories, and water supplies for cities. Regions of abundant rainfall are usually heavily forested, like the Amazon valley in South America, and parts of Equatorial Africa. In civilized countries lumbering is apt to be an important occupation in districts of heavy rainfall, as in Oregon and Washington in our own country, and in Southern Chile in South America. Where there is a moderate rainfall, and other conditions are favorable, there agriculture is possible, and farming becomes one of the chief occupations, as in the Mississippi and Missouri valleys in the United States, and in Western Canada. Districts which have a rainfall too small for successful agriculture, but are not by any means deserts, are often excellent grazing lands, as in the case of parts of Texas, Nebraska, and Kansas in the United States, and the Argentine Republic in South America. Where there is very little rainfall deserts are found. Cities are not built in deserts, because there are no occupations to attract large numbers of men. The inhabitants of the desert are wandering tribes, which move from place to place in search of water and food for themselves and their animals. Rain and snow cleanse the air, washing out impurities such as dust and smoke. Hence they are important agents in preserving health. Note the _kind_ of precipitation (rain, snow, hail, sleet); the _amount_ (heavy, moderate, light, trace); and the _time of the beginning and ending_ of the storm or shower. The record book must now be further subdivided into columns, to make room for the rainfall observations, in this manner:—— SAMPLE RECORD OF TEMPERATURE, WIND, STATE OF SKY, AND PRECIPITATION.