Feb. 17, 1871.] l T { Emerson. 
in Iowa; and connected it with Baron Burck’s account of the 
traditions he found among the Aztecs, of the migration of 
that race or tribe from the Northeast or Upper Mississippi 
and Missouri country. 
Mr. Coxe described a locality at Baker’s Run, on the West 
Branch of the Susquehanna, where the great freshets of 1868 
uncovered ancient hearths and numerous large vases, all of 
which were soon broken and scattered by the curious. 
The minutes of the last meeting of the Board of officers 
were read. 
Dr. Emerson introduced the subject of Lunar Influence, or 
e ’ 
supposed influence, upon the conditions of wet or dry weather. 
On Lunar INFLUENCE upon the Conditions of Wet or Dry Weather, 
by Dr. Emerson. 
(Read before the American Philosophical Soctety, February 17, 1871.) 
That the moon exerts such an influence, he said, is a very old opinion, 
widely spread at the present day, and even maintained by many distin- 
guished philosophers. A great deal of attention has been devoted to 
tabulating atmospheric observations in relation to the conditions of the 
weather at the quarterly changes of the moon. The results of such labo- 
rious investigations have, however, not been found to agree, some reports 
seeming to favor the existence of lunar influence in producing wet and 
dry weather, and others, to show that no such influences are exerted by 
the moon upon the hygrometric conditions of our atmosphere. Among 
the many who have engaged in investigating this subject I will only re- 
fer to the celebrated Italian philosopher Toaldo, whose observations were 
extended through a period of forty-five years, and to Pilgram, whose ob- 
servations were extended through a period of fifty-two years. For some 
reason which I shall not attempt to explain or examine, the conclusions 
of these indefatigable observers and inquirers were the very opposite of 
each other. 
The circumstance which has perhaps contributed most to strengthen 
the belief in lunar inflnmence upon the weather, is the well known agency 
exerted by the satelite upon the ocean and atmosphere, in the production 
of tides and barometrical fluctuations. Both of these phenomena are at- 
tributable to the force of gravitation, acting between the earth and moon, 
and giving rise to ocean and atmospheric waves. 
The atmosphere surrounding our earth consists : first, of a mixture of 
permanently elastic gases; and secondly, of a changeable atmosphere of 
watery vapor, depending for its suspension entirely upon heat. This 
A. P. §S.—VOL. XII—C 
