FORESTS AND WATER SUPPLIES. 23 



Division of the U. S. Department of Agriculture for 1889, with 

 a few changes in the nature of abbreviations: 



' 'The water capital of the earth may be regarded as con- 

 sisting of two parts, the fixed capital and the circulating cap- 

 ital. The first is represented not only in the waters on the 

 earth but also by that amount of water which remains sus- 

 pended in the atmosphere, being part of the original atmos- 

 pheric water-masses which, after the rest has fallen to the 

 cooled earth, remains suspended and is never precipitated. 



"The circulating water capital is that part which is evap- 

 orated from water surfaces, from the soil, from vegetation, 

 and which after having temporarily been held by the atmos- 

 phere in quantities locally varying according to the varia- 

 tions in temperature, is returned again to the earth by precip- 

 itation in the form of rain, snow and dew. There it is 

 evaporated again, either immediately or after having perco- 

 lated through the soil and been retained for a shorter or 

 longer time before being returned to the surface, or, without 

 such percolation, it runs through open channels to the rivers 

 and seas, continually returning in part into the atmosphere 

 by evaporation. Practically, then, the total amount of water 

 capital remains constant; only one part of it the circulating 

 capital changes in varying quantities its location, and is of 

 interest to us more with reference to its local distribution and 

 the channels by which it becomes available for human use and 

 vegetation than with reference to its practically unchanged 

 total quantity. 



"As to the amount of this circulating water capital we 

 have no knowledge; hardly an approximate estimate of the 

 amount circulating in any given locality is possible with our 

 present means of measurement: for it appears that so unevenly 

 is the precipitation distributed that two rain-gauges almost 

 side by side will indicate varying amounts, and much of the 

 moisture which is condensed and precipitated in dews escapes 

 our observation or at least our measurements entirely. Thus 

 it occurs tha.t while the amount of water calculated to be dis- 

 charged annually by the river Rhone into the sea appears to 

 correspond to a rain-fall of 44 inches, the records give only a 

 precipitation over its water-shed of 27.6 inches. 



