nge
is very high in summer. It is, therefore, to some extent, a useful
auxiliary, although of minor importance.

_The hygrometer_ is of less importance still. It is not in general use as
a practical guide to the changes of the weather, and does not deserve to
be.

A question, which has been much mooted, deserves a passing notice in this
connection--viz., whether our climate has gradually become ameliorated and
milder on the eastern part of our continent, since its settlement. I have
not space left for its discussion. Humboldt (Aspects of Nature, page 103)
is of opinion that there has been no material change. He says:

"The statements so frequently advanced, although unsupported by
measurements, that since the first European settlements in New
England, Pennsylvania, and Virginia, the destruction of many forests
on both sides of the Alleghanys, has rendered the climate more
equable--making the winters milder and the summers cooler--are now
generally discredited. No series of thermometric observations worthy
of confidence extend further back, in the United States, than
seventy-eight years. We find, from the Philadelphia observations,
that from 1771 to 1824, the mean annual heat has hardly risen 2 deg..7
Fahrenheit--an increase that may fairly be ascribed to the extension
of the town, its greater population, and to the numerous
steam-engines. This annual increase of temperature may also be owing
to accident, for in the same period I find that there was an increase
of the mean winter temperature of 2 deg. Fahrenheit; but, with this
exception, the seasons had all become somewhat warmer. Thirty-three
years' observation, at Salem, in Massachusetts, show scarcely any
difference, the mean of each one oscillating within 1 deg. of Fahrenheit,
about the mean of the whole number; and the winters of Salem, instead
of having been rendered more mild, as conjectured, from the
eradication of the forests, have become colder, by 4 deg. Fahrenheit,
during the last thirty-three years."

The facts hereinbefore stated show that there is nothing like a _regular_
amelioration; that the seasons differ during the same decade, and
different decades. The cold decade, from 1811 to 1820, has not been
reproduced. But it may be, and we know not how soon. Since that period
there has certainly been a change--for even the cold period from 1835 to
184