to TRANS. OF THE ACAD. OF SCIENCE. 



level in August, falls again in September nearly to the point 

 it bad attained in February, and then, in the last three 

 months of the year, rises slightly to nearly the level of March. 

 Another series of observations establishes the fact, that the 

 quantities of rain which descend in a given period of time, 

 increase regularly from January to July, and decrease again 

 from that month to January at the following ratio: 



Jan. Feb. Mar. April- May. June. July. 

 Inches of rain per hour 003 0-05 008 0-08 0-15 0>20 23 



Aug. Sept. Oct. Not. Dec. Mean. 

 0-19 0-13 0-10 0-07 0.06 0-10 



So that in July nearly 7 times as much rain is precipitated in 

 a given time as in January, and that the 4 inches of rain of 

 the former month fall, on an average, in the short period of 

 18 homs, while the less than 2 inches of rain (or snow) of 

 January require 55 hours for their precipitation. 



The number of days on which it rained or snowed in each 

 month during 29 years, from 1832 to 1801, is exhibited in the 

 subjoined table : 



«j 'u >> a i? bo 

 J3 5 .3 3 3 3 



■a s» 



Number 



Average, 78899 10 776787 93 

 < Minimum, 343444421233 69 

 U1 "<'•>- (Maxim., 12 13 15 14 16 18 14 14 12 13 11 12 115 



We have in almost every year, in the months of June, 

 July, or August, one or more falls of 2 and sometimes of 

 3 and even 4 inches of rain within a few hours, or even 

 within a single hour; in a few exceptional instances, the 

 quantity precipitated in 24 hours, or less, has reached as high 

 as 5 and 6 inches. This has happened four times in the year 

 1848 (.May 6th, June 2d, June 21st, and August 15th), and 

 in no other year as far as I have observed it. 



The second table (page 76) exhibits the amount of snow 

 which fell during the same period of time, the snow having 

 been melted and measured as inches of water. The aver- 

 age quantity, it will be seen, does not amount to quite 2% 

 inches, which corresponds to about 2 feet of snow. This 

 quantity of snow, however, never accumulates in our climate, 

 and, indeed, snow rarely covers the ground for more than 

 one, or at most two weeks at a time. 



The greatest average quantity is recorded for January; 

 next comes December ami February, and then March. In 

 April tails of snow have taken place only five times, and in 

 October only twice, in the last 2.'i years. 



The last column gives the quantities of snow for each win- 

 ter, from October of the previous year to April of the year in 



