t snow or
rain, and therefore is of no importance in this connection. The next day
the thermometer began to rise, and the barometer to fall. On the 5th it
clouded over, and the thermometer rose rapidly, and on the 6th it had
risen more than 25 deg., and snow fell. On the 7th it cleared off, the
thermometer fell rapidly, and the barometer rose. On the 8th the
thermometer had fallen to 21 deg. below zero, and the barometer had risen to
30.14. Another instance, in all respects similar, occurred the latter part
of the month. We shall see hereafter that these changes are precisely like
those which occur with us, and every where. That, as in the polar regions,
and whether the sun be present or absent, or obscured by clouds, and by
night as well as by day, the changes from warm to cold and from cold to
warm are sudden and great, and that the latter are connected with the fall
of rain and snow--that every where in winter it _moderates to storm_.

Many other instructive instances, especially in relation to the great
difference in the seasons in our own country, and upon the same parallels
elsewhere, might be cited if it were necessary. But they will more
appropriately appear in the sequel.

[Illustration: Fig. 1.

In the above cut the isothermal lines are Centigrade. The zero of the
Centigrade thermometer is the freezing point of water, or 32 deg. of
Fahrenheit. The boiling point of water is 100 deg. Centigrade, or 212 deg.
Fahrenheit. A degree of Centigrade is equal to one degree and four-fifths,
Fahrenheit. The 0 deg. line of the cut, therefore, is 32 deg. of Fahrenheit--the
line of 5 deg. above is 41 deg. Fahrenheit--the line of 5 deg. below is 23 deg.
Fahrenheit, and so on. The reader, who is not familiar with the difference
in the scale of the thermometer, is desired to remember this; for we shall
make occasional extracts in which the temperature is given in the
Centigrade scale.]

The cause of those irregularities, especially in the same seasons of
different years, and when very great, is often sought and supposed to be
found in the presence or absence of spots on the sun, ice floes and bergs
in the Atlantic, etc., etc. But neither the spots, nor ice, nor other
local causes produce them. The cause will be found in the character of the
arrangements we are considering, and the irregular action of the power
which controls them.

Nor is the temperature of the northern hemisphere, north of the tropics,
equal in the s