xed currents of air and aqueous vapor which rise from
the warm tropical ocean. They start with plenty of heat to preserve
the vapor as vapor; but as they rise they come into regions already
chilled, and they are still further chilled by their own expansion.
The consequence might be foreseen. The load of vapor is in great part
precipitated, dense clouds are formed, their particles coalesce to
rain-drops, which descend daily in gushes so profuse that the word
"torrential" is used to express the copiousness of the rainfall. I
could show you this chilling by expansion, and also the consequent
precipitation of clouds.

Thus long before the air from the equator reaches the poles its vapor
is in great part removed from it, having redescended to the earth as
rain. Still a good quantity of the vapor is carried forward, which
yields hail, rain, and snow in northern and southern lands.

Mountain Condensers.

To complete our view of the process of atmospheric precipitation we
must take into account the action of mountains. Imagine a south-west
wind blowing across the Atlantic towards Ireland. In its passage it
charges itself with aqueous vapor. In the south of Ireland it
encounters the mountains of Kerry: the highest of these is
Magillicuddy's Reeks, near Killarney. Now the lowest stratum of this
Atlantic wind is that which is most fully charged with vapor. When it
encounters the base of the Kerry Mountains it is tilted up and flows
bodily over them. Its load of vapor is therefore carried to a height,
it expands on reaching the height, it is chilled in consequence of
the expansion, and comes down in copious showers of rain. From this,
in fact, arises the luxuriant vegetation of Killarney; to this,
indeed, the lakes owe their water supply. The cold crests of the
mountains also aid in the work of condensation.

Note the consequence. There is a town called Cahirciveen to the
south-west of Magillicuddy's Reeks, at which observations of the
rainfall have been made, and a good distance farther to the
north-east, right in the course of the south-west wind there is
another town, called Portarlington, at which observations of rainfall
have also been made. But before the wind reaches the latter station it
has passed over the mountains of Kerry and left a great portion of its
moisture behind it. What is the result? At Cahirciveen, as shown by
Dr. Lloyd, the rainfall amounts to fifty-nine inches in a year, while
at Portarlington it is o