84 Canadian Record of Science. 
and the Alaskan islands, and then turns to sweep southward 
along the coast of British America. ‘The prevailing winds 
there, as everywhere else in the North Temperate Zone, are 
from the West; and these, after passing across thousands of 
miles of unobstructed and well-warmed ocean, come to us 
loaded with moisture. Warm air, you must remember, be- 
cause expanded by its warmth, will absorb more moisture 
than cold, so that these Pacific winds are saturated by the 
time they reach the shore. 
Now the mountains begin to do their part. 
One cannot appreciate how important is the influence of 
the mountains of the globe upon its climates, until he stops 
to think what a state of things would exist in their absence. 
Weather is simply the state of the atmosphere in respect to 
temperature, dryness or wetness and thelike. What affects 
these conditions causes a change in the weather. Were the 
surface of the continents flat, temperature would decrease 
from the equator precisely in ratio with the latitude, sub- 
ject only to the influence of winds from the ocean, which 
would blow with unfailing regularity and continuance, bear- 
ing a definite quantity of moisture and depositing it,probably 
unceasingly, in the same place, year after year. Heat and 
cold in climate would then be almost entirely a matter of 
summer or winter, or distance from the equator, and wet 
weather would belong wholly to certain zones, migrating 
with the seasons, while all the rest of the world would be 
arid. 
But the irregularities of the surface of the globe interfere 
with this, and make it a tolerable place to live. Without 
mountains (if we can conceive of such a state of things) the 
earth would scarcely be habitable—or at any rate comfort- 
able. But the hilis rise up toward the spaces of eternal 
frost which encircle the globe only a few thousand feet 
overhead, and act as condensers. The damp ocean air 
coming near them is cooled down to its dew point—that is, 
to a point where the invisible vapor of water it carries is 
changed into perceptible drops, clouds are formed and per- 
haps rain falls. 
