160 Lovering on Magnetic Observations at Cambridge. 
enterprise. The coefficients contained in the Tables on part of 
page 143, and the whole of page 144, were calculated by Mr. 
Hill, according to the method of Professor Pierce, of which some 
account was given on page 44 of our former paper. 
The instruments for these observations were furnished by the 
American Academy of Boston, and the buildings were paid for 
with funds raised by private subscription, with the assistance of 
Harvard University: but the whole labor of conducting the ob- 
servations has been the voluntary contribution of those who have 
been engaged in it. Under such circumstances, it cannot be 
expected that our observations can compare, for accuracy or com- 
pleteness, with those made at the regular Magnetic Observatories, 
by a personnel of five or more observers, who are commissioned 
and paid for giving their whole time and energy to this single 
object. 
JOSEPH LOVERING. 
Campriper, May 1, 1845. 
Errata.—The two observations on the Barometer at four and 
five o’clock on Dec. 6, 1842, are obviously inaccurate. I am not 
certain, from an examination of the original record, in what way 
the mistake was made, and what the true numbers should be, 
though I incline to think they should be 30.210 and 30.086. 
These observations would more properly have been omitted alto- 
gether; they crept into the printed copy from inadvertence. 
