162 
action on the skin, and secondly on the lungs through the 
air we breathe.* I therefore considered that a series of ob- 
servations on evaporation might be climatologically import- 
ant from several standpoints. 
The evaporation was made in a tin 27 cm. by 22 cm. by 
5 cm. (nearly 9 in. by 11 in.), painted white, and hung up 
by a wire in a screen 90 cm. wide by 75 cm. by 60 cm. 
high, placed in the shade of a music pavilion. This pavi- 
lion (27 feet diameter) was nothing more than a roof 
supported by twelve pillars, thus allowing a free passage of 
air, but protecting the screen from the sun during the 
winter months of November, December, January, and Feb- 
ruary, with the exception of a few minutes during the 
last days of the month ; also during the shortest days the 
sun shone for a short time between the pillars, but then the 
screen was protected by cane blinds. 
On the first of December there was a thaw most of the 
day, and three times in the month a partial thaw. In 
January there was no thaw, and until the 23rd of February 
nothing more than the melting of a few drops in the warmest 
part of the day, but after that the ice was mostly thawed. 
The observations of value are those when the ice was not 
melted, as when there was a thaw the evaporation would 
neither represent that of ice nor of water, as then the tem- 
perature of the water would remain at freezing point 
although the air might be many degrees higher, so that 
then little, or in extreme cases no evaporation might take 
place. 
During the months of December, January, and February, 
the dew point was never above freezing ; at nine o’clock 
the temperature of evaporation was also never above 32 ; 
at 11 a.m. it was twice slightly above; at 1 p.m. seven 
* In climatological considerations tlie amount of moisture carried off 
from the lungs receives much more attention than that removed by the 
skin, but as the amount removed in health, as perspiration, is greater 
than that expired, both must be looked upon as of primary importance. 
