8 DR. G. S. WEST ON THE ALGÆ OF 
The temperatures of the water are surface temperatures taken at a depth of 
from six to twelve inches. The lowest recorded temperature was 10° C. 
(90° F.), which occurred on each of the three dates July 1st, Aug. 5th, and 
Sept. 2nd, 1905 ; the highest was 244° C. (76° Е.) on Feb. 10th, 1906. 
The air-temperatures naturally show a greater range of variation, from 
1117 C. (52° Е.) on Oct. Tth, 1905, to 356^ С. (96° F.) on Jan. 6th, 1906. 
On June 3rd, 1905, the temperatures of the air and water exactly coincided 
at 12-9" С. (54° Е.). 
In the accompanying chart (text-fig. 2) the thermometrie observations 
are plotted out, and they show at a glance the smaller rise or fall of the 
Fiz. 2. 
1905, 1906. 
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Temp. of Air | -----+--- d 
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Temp. of Water| auto 
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РЕВ. MAR, APR. MAY JUNE JY. AUG. SEP OCT. NOV. DEC. JAN. FEB. 
4n. an. Let 6th 3rd Is Sth $4 ZE 4th Bnd 6th 10th. 
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Chart showing the variations in the temperature of air and water at the Yan Yean 
Reservoir, Feb. 1905 to Feb. 1906. 
temperature of the water corresponding to a greater rise or fall of the air- 
I | 5 H 
temperature. It will be noticed that in no instance does the recorded 
air-temperature fall below the minimum temperature of the water *. The 
* This feature is due to the almost entire absence of prolonged frosts, and is not shown in 
a similar comparative series of observations relating to any lake in the temperate and more 
northerly parts of Europe, in which the record of air-temperatures would several times 
reach a minimum considerably lower than any shown in a correlated record of water- 
temperatures. 
