B. TERRESTRIAL PHYSICS AND METEOROLOGY. 63 



B. TERRESTRIAL PHYSICS AND METEOROLOGY. 



AMOUNT OF FOKCE DERIVED BY THE EAETH FROM 



THE SUX'S HEAT. 



An interesting computation has been made of the amount 

 of force imparted to the earth by the sun's heat. According 

 to the best investigations that have been made, there is re- 

 ceived in one minute enough heat to raise the temperature 

 of five and a half cubic miles of water one degree Centigrade. 

 If, now, we compare this with the work done by a given 

 amount of heat, as utilized in a steam-engine, it will be found 

 that the heat sent to the earth in the sun's rays during the 

 space of one minute is able to do as much work as would be 

 done by two thousand steam-engines of one hundred horse- 

 power each, working continuously for the space of four thou- 

 sand years. , 



What becomes of this inconceivably great amount of power 

 is worthy of consideration ; and we begin to realize the na- 

 ture of the problems of the future scientists when we reflect 

 that by far the larger part of this heat force expends itself 

 upon the earth in actual work, only a small portion of it 

 being radiated into space. Of course the result accomplished, 

 such as the maintenance of the temperature of the earth, 

 ocean, and atmosphere, the stimulating of animal and vege- 

 table life, etc., etc., must be the equivalent of the power re- 

 tained by our globe. Mitth. natur for sell. Gesellsch.^ Berne, 

 1871,xxxix. 



EIVER TEMPERATURES. 



The United States Signal Corps has recently extended its 

 series of observations in the form of a daily record of the 

 surface and bottom temperature of the rivers and harbors 

 upon which the several stations are situated. This, while of 

 much interest in a meteorological point of view, is also of 

 practical importance in connection with the subject of intro- 

 ducing useful food fishes into the rivers and lakes of the 

 United States, as lately provided for by Congressional enact- 

 ment. It is well known that the possibility of introducing 



