OBSERVATIONS. 79^ 



corresponding to .69 of an inch of mercury, or 

 9.6 inches of water, the temperature of the air, 

 at the time, being ,73'^.5. The difference be- 

 tween the quantities of water contained in a 

 vertical column of the atmosphere, in these par- 

 ticular instances, is 8.2 inches. 



It was my intention to introduce, in this place, 

 a series of observations on the evaporation from 

 water, but my gage was so unfavourably situ- 

 ated, and I experienced so much difficidty in 

 protecting it sufficiently from rain, frost, and 

 birds, without, at the same time, impeding, in a 

 great measure, the free admission of air and 

 sunshine, that the results were considered too 

 incorrect to be admissible here ; they are, there- 

 fore, withheld ; and I the less regret this circum- 

 stance, because the quantity of water evaporated 

 each month throughout the year, may always 

 be found from the mean monthly temperature 

 and point of deposition.* 



* See the second part of the 5th volume of the First Series of 

 the Society's Memoirs, p. 588. 



