86 Lovering on Magnetic Observations at Cambridge. 
The observations which are here offered to the Academy, and 
through them to the brotherhood of magnetic observers, were 
taken during a period of a little more than a year, from the autumn 
of 1841 to the winter of 1842, as will be seen by reference to the 
printed records. It was not expected, at the commencement of 
the work, that observations would be made at Cambridge on any 
but the regular Term-days, since all the time that could be given 
to this object was only what the observers might be able to spare 
from their ordinary labors. At the suggestion of Professor Peirce, 
however, whose services to the Observatory have been invaluable, 
an Association was formed among members of the Senior, Junior, 
and Sophomore classes then in College, under the name of the 
Meteorological Society of Harvard University. By the help of this 
Association, observations were made on the Barometer, Thermom- 
eter, and the three Magnetic Elements, with the attached Ther- 
mometers, during the whole day and night, at intervals of two hours, 
one hour, or half an hour, as other duties rendered it convenient. 
The magnetic observations were made with the three instruments 
described at the close of my former communication, where the 
mode of observing is given. This Association was active for 
more than a year, and I am chiefly indebted to the zeal and 
diligence of its members for the materials of this paper. When 
we consider by whom the work was undertaken, —by students, 
who had little leisure to spare from their academic exercises, — 
by the young, who might be expected to seek more exciting 
relaxation than could be received from watching by night as well 
as day the vibrations of a steel bar,—and when we recall the 
care, accuracy, and spirit with which it was carried forward, we 
feel that the Academy, and that American science, are under 
great obligation to those young men who assumed voluntarily 
