6 ©. E. Dutton—Effect of a warmer Climate upon Glaciers. 
body from a position of stable equilibrium which it seeks to 
reéstablish, is a case of the conversion of kinetic into potential 
energy. “The radiant energy which falls upon the earth is 
artially converted into potential which is in turn expended in 
producing the movements of the air. Having referred these 
movements back to their cause and having put the conditions 
of the question into the most general and comprehensive form, 
may now ask again, would the wind-potential be greater if 
solar radiation were to increase? Undoubtedly it would. But 
in what ratio? To this latter question, | believe, a sufficiently 
approximate answer can be given. The problem is purely a 
thermodynamic one. 
(11.) The atmosphere, considered with reference to its winds, 
may be regarded as a series of thermodynamic engines oper- 
ated by an expansible and nearly perfect gas receiving heat and 
converting it into work. The amount of energy available for 
this work is directly proportidnal to the difference (in any given 
case) between the absolute temperature which the body of air 
the sphericity of the earth, its rotation and seasons, its hetero- 
geneous surface—are in the main fixed in nature and constants ; 
while the motive power is the sun’s radiant energy. And since 
the solar radiation and the temperature-differences of the air 
are both heat-quantities, pure and simple, we have, apparently, 
no alternative but to conclude that they are proportional to 
each other. But the exact form of the ratio is unknown. 
Nevertheless, if we assume it to be a simple ratio for any range 
of variation in the amount of solar radiation which could be 
reasonably postulated in connection with the present discussions, 
we shall certainly commit no large error. Still less shall we 
err if we assume that the inequalities in the heating of the air 
are proportional in a simple ratio to the mean absolute tempera- 
ture of the air at the earth’s surface, and if that temperature 
were raised by increased solar radiation the inequalities which 
cause the winds would increase in the same ratio. 
be disposed to postulate? Would 20° C. be sufficient ? 
ing the mean temperature of the earth’s atmosphere at the 
surface to be (274°+16°) C. and adding 20° to it, we have 310°, 
and the ratio of 290:310=1-07, or an increment of seven per 
cent in the absolute temperature of the atmosphere. Assumin 
that the wind potentials are every where increased in like ratio, 
aud remembering that the velocity of the wind is proportional 
to the square root of the energy expended in producing it, the 
