* 
. ofessor e 
: Which has reference to m: 
: “ia 
J. Croll—Professor Newcomb’s “Rejoinder.” 347 
the land. The result is that the temperature of equilibrium 
of the ocean must be higher than that of the land. In other 
words, before the ocean can manage to throw off its heat into 
space as rapidly as it is receiving it, its temperature must be 
higher than that of the land. 
he foregoing conclusion follows so obviously from the 
known properties of aqueous yapor and the principles of ther- 
modynamics that I can hardly believe Professor Newcomb will 
eall it in question. But he will ask how can the transparency 
of the ocean for heat-rays, the mobility of its particles, and 
the greater store of heat which it possesses, be a reason why 
its mean temperature should be higher than that of the land? 
I thought I had made all this clear. The reason becomes ap- 
parent when we consider why it is that the surface of the ocean 
during night and also during winter is warmer than the surface 
of the land. The ocean in temperate regions seldom sinks to 
the freezing-point, while the land is frequently frozen for 
months. The cause is obvious enough: at night, when the 
Surface of the ocean becomes cool, the cold particles sink and 
their places are supplied by warm particles from below, and so 
long as the heat stored up remains, the surface can never be- 
Tays, it would be impossible that the ocean could obtain a sup- 
Ply of heat sufficient to maintain its surface-temperature during 
the 
Warmth e 
Atlantic, 
ocean is consumed 
tion of this he 
durin 
heat fro ‘at 
former ig rere it not 
Store m ‘ | to part with 
So much of its heat to the land during wi ar and still maintain 
Newcomb’s mise 
