CHAP. VII.] 



DEEP-SEA TEMPERATURES. 



297 



During these experiments the water in the cylin 

 der was of course maintained as far as possible at 

 the same or at a known temperature ; a certain 

 amount of calorific effect must, however, he pro 

 duced by the sudden compression of the water, and 

 the next series of experiments was performed in 

 order to determine the amount of that effect. Three 

 of Phillips' s encased maximum thermometers (Sir 

 "William Thomson's design), being entirely protected 

 from any effect from compression, were employed for 

 this purpose, with the following result : 



Pressure, 6,817 Ibs. = 2,500 fathoms. 



So that this source of error is absolutely trifling. 



The true error of the Miller-Casella thermometer, 

 as deduced from these observations, is 



For 250 fathoms 0'079 C. 

 For 2,500 fathoms 0'79 C. 



