Popular Science Monthly 



227 



addition to its regular stations 

 (located mostly in important 

 towns), about two hundred spe- 

 cial snowfall stations in the 

 mountains and foothills. The 

 Bureau has also developed spe- 

 cial forms of measuring appara- 

 tus appropriate for such loca- 

 tions. 



The relation of the depth of 

 snow to its water content is quite 

 variable. It has been custo- 

 mary, when more exact deter- 

 minations were impracticable, to 

 regard ten inches of snow as 

 equivalent to one inch of rain- 

 fall, but this assumption is only 

 correct for snow of average 

 density. In problems of water- 

 supply the depth of snow is of no 

 consequence in comparison with 

 the water content, and the latter 

 can be obtained either by melt- 

 ing the snow before measure- 

 ment, or by weighing the snow. 

 The latter process is generally 

 much simpler and is the one 

 utilized in the type of gage used 

 by the Weather Bureau at its 

 mountain stations. 



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The Latest Fashion in 

 Snow- Measurers 



The accompanying picture 

 shows a gage recently designed 

 by Professor Marvan, Chief of the Weather 

 Bureau, suitable for measuring either rain 

 or snow. At the top is seen a trumpet- 

 shaped wind-shield, and in the middle the 

 cylindrical can or collector into which the 

 precipitation falls. The can rests upon a 

 central support, which can be raised or 

 lowered for placing or removing the 

 collector. In making an observation, the 

 can and its contents are removed and 

 weighed by means of a spring balance, grad- 

 uated to give the rainfall directly in inches 

 and hundredths. The type of gage here 

 shown is used for daily observations, but a 

 modified form, with much enlarged collector, 

 is used where observations can only be 

 made at long intervals — in some cases 

 only once a season. In this gage oil 

 films are sometimes used to prevent evapo- 

 ration. 



Besides snow gages the Bureau uses snow 

 stakes for measuring the depth of snow at 

 various points around the station. The 

 latest form of snow stake consists of a heavy 



The Marvin gage for measuring rain or snow. At the top 

 is a trumpet-shaped wind-shield and in the middle a cylin- 

 drical can, 'or collector into which the precipitation falls 



cypress stick of square section, painted 

 white to minimize radiation elTects, and 

 bearing on one of its faces a scale of enameled 

 iron, graduated in inches. In the picture of 

 the measuring stick on page 229 the num- 

 bers attached to the scale represent tens of 

 inches; I means 10 inches; 2, 20 inches; etc. 

 These graduations can be read at a distance 

 by means of binoculars or a telescope. The 

 stakes are permanently installed in appro- 

 priate locations. 



Lastly, the ambitious attempt has been 

 made in recent years to ascertain, early 

 each spring, the total amount of water 

 available in the form of snow over wild 

 mountainous tracts adjacent to certain 

 irrigation projects and remote from the 

 fixed stations. "Snow surveys" of this 

 sort were first carried out by Professor 

 Church, of the University of Nevada, 

 in the Sierra Nevada, and by Messrs. 

 Thiessen and Alter, of the United 

 States Weather Bureau, in the mountain- 

 ous districts of Utah. 



