It is perhaps too early to determine rigorously the
true temperature of these points.
A noticeable fact also is this,--that places in the same latitude
rarely receive the same amount of heat. Quebec, in British America,
and Drontheim, in Norway, enjoy about the same quantity, while the
former is in 47 deg. and the latter in 68 deg. N. Lat. The mean winter
temperature of Pekin, 39 deg. 45' N. Lat., is 5 deg. below the freezing-point;
while at Naples, which is north of Pekin, it seldom, if ever, goes
below it, and Paris, 500 miles farther north, has a mean winter
temperature of 6 deg. above the freezing-point. The city of New York,
about 11 deg. south of London, has a winter temperature of much greater
severity. The mean temperature of the State of New York, as determined
by a long series of observations, is 44 deg. 31'.
The mean temperature of countries is found to be very stable, and but
very small variations have been detected in modern times. But that
there have been important climatic changes, since the Christian era,
cannot be doubted, unless we doubt history. Not many centuries ago, it
was a common thing for all the British rivers to freeze up during the
winter, and to remain so for several months.
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