105 
EVIDENCES OF THE AGKE OF ICE. 
By HENRY WOODWARD, F.R.S., F.G.S., &c. 
[PLATE III.] 
NLY a few years ago it was looked upon as an article of 
faith among geologists that the whole globe was once in 
a molten, incandescent state, and that the conditions of tem- 
perature now prevailing on the surface of the earth had been 
produced in process of time by the slow and gradual cooling of 
the once fused and glowing mass. But whatever may be the 
unknown heat of the deeper strata, that of the surface results 
solely from the great source of heat, the centre of attraction of 
our planetary system — the sun. 
The oscillations between heat and cold that we experience 
from day to night, and from summer to winter, all depend on 
the laws of absorption and radiation of heat given off by the 
sun to the earth, or radiated by the earth into stellar space. 
If the earth were a globe of perfect regularity, presenting on 
its surface no contrast of land and sea, plateaux and plains, 
snow and verdure, a nearly equable distribution of climates would 
be established over its whole extent, and one could exactly 
measure the degrees of heat by those of latitude. 
But such we know is not the case. Every place has its own 
climate. Such variations depend on the elevation of the land 
above the sea ; the position of a place, whether inland or on 
the coast ; the direction and height of its mountain chains ; the 
extent of its forests, savannahs, and cultivated lands ; on the 
width of its valleys, the abundance of its rivers, the outline of 
its coast ; on marine currents, prevalent winds, clouds, rain, 
fogs, &c. ; these varied causes constitute, together with the lati- 
tude, what is called 44 the climate of a country.” * 
Undoubtedly the most important climatal phenomenon is 
that of temperature, for to heat we probably owe all the move- 
ments of the atmosphere which we call winds. Parts of the 
* Elisee Reclus, u La Terre.” 
NEW SERIES, VOL. I. — NO. II. I 
