38 



GEOLOGICAL SURVEY OF WISCONSIN. 

 Table op Rain-Eall at Milwavk-eb— continued. 



This table shows that the rain in Wisconsin is generally very well 

 distributed through the several months, seasons and years; the gen- 

 eral average for thirty-one years being 30.27 inches, varying from 

 20.54 in 1845, to 44.86 in 1858; the greatest amount in any one month 

 was 9.03 inches in August, 1850, and the least 0.10 in January, 1857. 

 The most rain upon an average falls in J une ; the least in February ; 

 the three months of summer have been supplied, upon the average, 

 with the most rain, the three months of winter, the least; while the 

 spring months have a little more than those of autumn. 



During nearly half the years covered by the table the rain -fall dif- 

 fered but little from the general mean; while nine were considerably 

 in excess, and eight were supplied with less than 28 inches. 



Prom the published results of observations collected by the Smith- 

 sonian Institution, it appears that the average rain-fall at about 

 twenty stations in "Wisconsin, or on its immediate border, was about 

 three inches more than at Milwaukee. 



The annual supply of falling water, as shown by this table, is 

 equivalent to a sheet of water two and three-fourths feet deep, spread 

 evenly and uniformly over the whole area of the state.- The most care- 

 ful investigations have shown that this is sufficient to account for the 

 outflow of all our lakes, rivers and springs; the total quantity thus 

 carried away being, in our climate, found equivalent to only about 

 one-fourth of the total rain-fall. The remainder is evaporated, and 

 thus returned to the atmosphere, either directly from the surface, or 

 after having performed service in the growth of plants. The quantity 



