470 



TRANS. ST. LOUIS ACAD. SCIENCE. 



January 96- 1 



February 94-2 



March ii4-7 



April ii9'7 



May 126.9 



June 146.5 



July 13S.1 



August 121. S 



September 102.5 



October 90-4 



November 100.9 



December io5-5 



Year 1357-3 



The map showing the average rainfall for the year gives by a 

 similar treatment 1406 cubic miles, which differs from the value 

 deduced from the monthly maps by less than two and one half 

 per cent. 



This water would fill a ditch half a mile deep and a mile 

 wide, reaching nearly from New York to San Fi-ancisco. 



The average rainfall per second on the whole country would 

 fill a cubical box whose edges are 187 feet. 



According to measurements which I have made on the velo- 

 city of falling rain-drops, the average velocity is between 180 to 

 200 ft. per second. This total rain is therefore equal, roughly, 

 to a stream of water 1S7 ft. square in section delivered upon the 

 earth with the velocity of falling rain-drops. 



Similar methods are used in finding average temperatures of 

 a country or a state. Such integrals afford a reliable means of 

 comparison of any monthly values with normal values, and cer- 

 tainly afford the most delicate method of testing any systematic 

 change in the climate of a county or any part thereof. 



