422 Scientific Proceedings, Royal Dublin Society. 
Between 80° N. lat. and 70° N. lat., at present ; 
ao 2489 
(460)? 
a= 160°5° F below zero. 
A—460° F 
” 3? 
In former times, Miocene, Jurassic, and when albumen coagu- 
lated, we have H, the heat supplied and radiated annually, 
depending on four quantities, viz. :— 
Ist. Sun-heat. 
2nd. Earth-heat. 
3rd. Thermal properties of the earth’s atmosphere. 
4th. Star-heat. 
Of these four quantities, the fourth only, or star-heat, is 
known; for we may safely assume that, during geological time, 
the earth and solar system were as far removed as they are now 
from the influence of any star except that of the sun itself, and 
that the heat derived from stars was always of no account. 
As we cannot separate the effect (in geological times) of the 
influence of the sun, earth, and atmosphere, I shall consider the 
following three cases, from which, as I believe, much instruction 
may be derived— 
(A.) The sum, as the sole source of heat, the earth and atmos- 
phere conditions being as at present. 
(B.) The earth, as the sole source of heat, the sun and atmos- 
phere conditions being as at present. 
(C.) The thermal properties of the earth’s atmosphere being 
varied, while the sun-heat and earth-heat remain as at present. 
(A.)\—Sun-heat regarded as the sole cause of changes in Geologi- 
cal Clumates. 
In this case we have— 
H=a (6 +a) (0+A). (9) 
where a, a, A, have the values just given, and at 80° N. lat. 
@ = 45°F, . Present time. 
6*= 44:3 ,, . Miocene time. 
= Gee > . Jurassic time. 
0 =122:0 ,,  . Coagulation of albumen. 
PBy, interpolation, for at Disco, 70° N, lat., @=55-6° F., and at Grinnell Land, 
81° 44’ N. lat., 9=42°8° F, 
