W. P. Blake on Evaporation on the Tulare Lakes. 267 
It will be observed that the evaporation ceased at night. The 
temperature of the air was always rapidly reduced after sunset, 
but there was no dew. As these low, night temperatnres‘did not 
influence the result, we may take the mean of the day tempera- 
tures both for the air and the water at the time of observation,— 
subject to the slight error caused by the deficiency of observa- 
tions on the 26th and 28th—and obtain approximately the tem- 
perature conditions of the air aud water for that amount of evap- 
oration. These results are, for the air 83°-9, for the water 71°-5; 
time, 46 hours. Height of barometer 29-30. 
Although at the time of these experiments I regarded the air 
as exceeding dry, I have since been forced to the conclusion that 
its condition was not the most favorable to great and rapid absorp- 
tion of water. The crests of the ranges of the Coast Mountains 
are not greatly elevated in that region—being, probably, less than 
4000 feet—and during the day they are much heated by the sun: 
they do not, therefore, cause the precipitation of all the moistnre 
which the air brings with it from the sea, and its thorough desic- 
cation is not accomplished. A great part of its moisture is ne- 
cessarily retained, and a capacity for the absorption of more is 
given by the elevation of temperature which it snffers among the 
Mterior ranges and valleys of the coast, and finally upon the 
broad and heated plain. It is well to consider these conditions 
iv connexion with the experimental results, and if the air is thus 
highly charged with moisture, the quautity taken up must be 
regarded as very large. At the rate of one quarter of an inch a 
day, seven inches and a half in depth will be removed in thirty 
days, or seven feet seven anda quarter inches in one year. Ac- 
cording to Dr. G. Buist, the amount of evaporation from the sur- 
ace of water at Aden, on the Indian Ocean, “is about eight feet 
for the year.”* ‘The bases of this statement is not given, but it 
18 interesting to notice that the amount agrees with my experi- 
mental result. F 
lhe facts which have been given, derive importance and in- 
terest from the bearing they have upon the phenomena of the 
evaporation from the surface of the Tulare lakes. These lakes 
n Joaquin, a distance, if measured along the summit of the 
Mountains, of nearly 200 miles. Among t 
empty into them, are three of considerable magnitude, Kern 
Tiver, King’s river, and the Caweea or Four creeks. The flow 
In these streams is constant through the year, and they are often 
Very much swollen by the melting of the distant snows, even 
* Trans, Bombay Geographical Society, vol. ix, 1849-50, p. 39. 
