1316. CLIMATE, Humidity.—
It has
been an opinion pretty generally received
among philosophers, that the atmosphere of
America is more humid than that of Europe.
Monsieur de Buffon makes this hypothesis one
of the two pillars whereon he builds his system
of the degeneracy of animals in America. Having
had occasion to controvert this opinion of
his, as to the degeneracy of animals there, I
expressed a doubt of the fact assumed that our
climates are more moist. I did not know of
any experiments which might authorize a denial
of it. Speaking afterwards on the subject
with Dr. Franklin, he mentioned to me
the observations he had made on a case of
magnets, made for him by Mr. Nairne in
London. Of these you will see a detail, in the
second volume of the American Philosophical
Transactions, in a letter from Dr. Franklin to
Mr. Nairne, wherein he recommends to him to
take up the principle therein explained, and
endeavor to make an hygrometer, which, taking
slowly the temperature of the atmosphere, shall
give its mean degree of moisture, and enable us
to make with more certainty, a comparison between
the humidities of different climates.
May I presume to trouble you with an inquiry
of Mr. Nairne, whether he has executed the
Doctor's idea? and if he has, to get him to
make for me a couple of the instruments he
may have contrived. They should be made of
the same piece, and under like circumstances,
that sending one to America, I may rely on
its indications there, compared with those of
the one I shall retain here [Paris]. Being in
want of a set of magnets also, I would be glad
if he would at the same time send me a set, the
case of which should be made as Dr. Franklin
describes his to have been, so that I may repeat
his experiment.—
To Mr. Vaughan. Washington ed. ii, 82.
(P.
1786)
