REPLY TO CRITICS. 



librium is never gained until the rate at which a body 

 receiving heat is equal to the rate at which it is 

 losing it; but as equal surfaces of sea and land receive 

 from the sun the same amount of heat, it therefore 

 follows that in order that the sea may get quit of its 

 heat as rapidly as the land, it must stand at a higher 

 temperature than the land. The temperature of the sea 

 must continue to rise till the amount of heat thrown off 

 into space equals that received from the sun; when this 

 point is reached, equilibrium is established and the tem- 

 perature remains stationary. But, owing to the greater 

 difficulty that the sea has in o-etting rid of its heat, the 



t/ O CD ' 



mean temperature of equilibrium of the ocean must be 

 higher than that of the land ; consequently, the mean 

 temperature of the ocean, and also of the air immediately 

 over it, in tropical regions, should be higher than the 

 mean temperature of the land and the air over it.' 



I had thought that the foregoing expressed, with 

 sufficient clearness, the reasons why the ocean ought 

 to be warmer than the land ; but I find that Professor 

 Newcomb, in his " Rejoinder," still maintains that my 

 views on this point are opposed to the fundamental 

 laws of thermodynamics. But surely he must have 

 misapprehended my reasoning. 



The temperature of a body can remain stationary 

 only when the rate at which it is losing equals that 

 at which it is receiving heat. If heat be lost more 

 rapidly than it is received, the temperature will fall. 

 The fall of temperature will diminish the rate of loss 

 till the rate of loss equals the rate of gain. After this 

 the temperature becomes stationary. If we have two 

 bodies, A and B, the same in every respect, each 

 receiving (say from the sun) the same amount of heat 

 in a given time, and if the only difference between 

 them be that A has a greater difficulty than B in 



