Meteorology. 



331 



The mean number of days on whicli rain fell for tlie same 

 period is 73 per year, and the number of days on -wbicb snow 

 fell is 43, making a sum of 116 days on wliich precipitation took 

 place, leaving 249 fair days as a yearly mean for the V years, — 

 there is on an average of about 110 nights suitable for astronomical 

 purposes in each year. 



The yearly mean amount of rain for the same period vras 43. 

 004 iaches in depth on the surface, and the depth of snow also 

 on the surface, shows a yearly mean of 95.76 inches. The 

 monthly mean for snow and rain are as follows : — 



January, . . 

 February, . 

 March, . . . 

 April, .... 



May, 



June, 



Inches of | 



Rain. 



Snow. 



0-600 



22-38 



0-167 



25-00 



0-380 



18-79 



4-624 



2-46 



4-386 





6-013 





Inches of 



July, 



August, . . . , 

 Septeml)er, 

 October, . . 

 November, . 

 December,. 



Rain. 

 3-003 

 5-908 

 5-831 

 6-063 

 5-055 

 0-940 



Snow. 



1-80 

 4-34 



n-71 



This gives a mean of 52,380 inches of rain and melted snow, 

 this is reduced by the Smithsonian formula, which does not hold 

 good or correct for low temperatures, and I think 1 to 8 would 

 be more accurate. The greatest amount of rain which fell in 24 

 hours, on record here, was in September 1853, and amounted to 

 5,142 inches, but this is unusual ; you will perceive that we are 

 little more than five months without snow. 



The difficulty in this climate of measuring the amount of 

 evaporation from the surface of water, except for 7 months of the 

 year, owing to frosty nights, has induced me to undertake the 

 registration of the amount of evaporation from the surface of ice 

 during the remainder of the year, (5 months) so as to compensate 

 in some measure for the defect in the observations on the amount 

 of evaporation from the watery surface. These combined obser- 

 vations give a mean of more than 30 inches as the amount of 

 water evaporated. The evaporator is shaded from the sim and 

 rain, but is exposed to the currents of wind, so is also the icy 

 surface in winter. 



I am led to believe this amount is tolerably correct. The mean 

 amount of evaporation from the surface of water alone for the 7 

 months is nearly 21 inches, the remaining amount being furnished 

 by the evaporation Avhich takes place from the surface of ice dur- 

 ing the remaining 5 months. 



