THE USE OF WEATHER INSTRUMENTS 195 



amounts. The rain caught in it runs through the funnel, A , into 

 a smaller can, C, of the proper diameter to multiply the actual 

 depth of rainfall by ten. The ruler is marked into tenths of an 

 inch, and each tenth measured in the smaller can stands for 

 one-hundredth of an inch actual rainfall. In very heavy 

 rains, some of the water overflows into the outer can, B, and has 

 to be poured back for measuring. 



218. The Measurement of Snow. For measuring snowfall 

 the outer part of the same gauge is used alone. When there 

 is little wind the snow falling into the gauge will generally be as 

 deep as that outside, and the gauge measurement will be ac- 

 curate. But usually some snow is blown out by the wind, and 

 it is necessary to measure the fresh snow outside in several 

 places to find its average depth. Then at a point where the 

 new snow is of that average depth, cut out a section of the 

 new snow by using the top of the inverted empty snow gauge 

 after the manner of a biscuit cutter, and slide a shingle or 

 piece of tin across the mouth of the gauge underneath the 

 snow before lifting. The snow thus picked up is melted and 

 the water measured and recorded as if it were rain. The 

 density of snow varies considerably in different storms and in 

 different portions of the country. It may require anywhere 

 from about 7 in. to 30 in. of fresh snow to yield 1 in. of water. 



The depth of snow affects winter travel, lumbering, rail- 

 roading, teaming, the care of live stock on farms and ranches, 

 and several other lines of business. It also influences the 

 condition of the soil, of fall sown crops and of meadows and 

 pastures during the following summer. The amount of water 

 in the snow is important to agriculture, to many irrigation 

 systems, to river navigation, and to districts subject to flood- 

 ing when the snow melts. Moreover, unless snow is re- 

 duced to water, accurate comparisons cannot be made of 

 the precipitation of different years, or that of winter and 

 summer, or of warm and cold regions. 



Peoria, 111., in 1910, had 22.3 in. of rain and 8 in. of snow; and in 1914, 

 21.1 in. of rain and 36 in. of snow. In the total amount of water, 



