, even at that season, are chilly. They were above the latitude
of 50 degrees; and although in England, which is on that parallel, it is
not very cold of a spring night, it must be remembered that the line of
equal temperature--in the language of meteorologists the "_isothermal
line_,"--is of a much lower latitude in America than in Europe.

Another fact worth remembering is, that upon the eastern or Atlantic
coast of the American Continent it is much colder in the same latitude
than on the western or Pacific side. The Pacific "sea-board" in its
climate is more like the western edge of the old continent. This would
seem to indicate that the climate of a coast country is much influenced
by the side upon which the ocean lies, whether east or west. This in
reality is the case, for you may observe on your map that the western
coasts of both the "old world" and the "new" are somewhat similarly
placed in regard to their oceans, and hence the similarity of their
climates.

There are many other causes connected with this; such as the direction
of winds, and the different effects produced by them on the atmosphere
when they have passed over water or over land. It was, and is still by
many people believed, that the winds are produced by the air becoming
heated in a particular place, and then ascending, and leaving a "vacuum"
into which the colder air rushes from all sides around. This "rushing,"
it was supposed, made the wind. To some extent this theory is true, but
there are several other causes that operate in producing wind.
Electricity--an agent hitherto but little known, but one of the most
important elements of our Earth--has much to do with the winds; and the
revolution of the Earth on its own axis has also an influence upon them.
Indeed it is to be wondered at, that mankind should have so long
remained satisfied with the very unsatisfactory theory of the _heated
air_. But it is not to be wondered at either, when we consider how
little mankind has had to do with these things--when we consider that as
yet nearly every country upon the face of the globe is despotic; that
the whole time of the great body of the people is occupied in a struggle
for life--occupied in toiling for a few, who by the most cunning devices
rob them of the fruits of their toils--rob them so skilfully that the
poor blinded masses have grown to consider eternal toil as the _natural
state of man_--nay more, are ready to persecute him who would el