f 
36 A. D. Bache on Declinometer Observations. 
Art. IV.—General account of the results of the discussion of the 
Declinometer observations made at Girard College, Philadelphia, 
between the years 1840 to 1845, with special reference to the eleven — 
year period; by A. D. Bacuz, Superintendent of the U.S. 
Coast Survey. 
[Communicated to the American Association for the Advancement of Science, by — : 
nt.] 
authority from the Treasury Departme 
lege, the observations being made under the patronage of the — 
, and finally completed for the 
use of the Topographical Bureau of the War Department. 
hese observations were made under my direction and superin- 
tendence. The series commenced in May, 1840, and with short — 
interruptions terminated in June, 1845, thus furnishing a five 
years series of magnetic observations taken bi-hourly up to Oct. 
1848, and after that date hourly. The readings of each mag- 
netic element were united into means, and were also presented 
graphically (in the fourth volume of the record). ‘This was 
one under my direction by J. Ruth, Esq., but owing to other — 
laborious duties the record’ could not be submitted to a more — 
complete reduction. I have now resumed the subject by the as- — 
sistance of Charles A. Schott, Esq., Assistant in the Coast Sur- 
results, it is nevertheless desirable to obtain results from inter- 
mediate observatories as confirmations or as corrections. In the 
investigation of the disturbance-law at Point Barrow, when 
compared with the same at Toronto, a very remarkable mutual 
* It may be proper to state that this work has been performed out of Office 
hours, and at my own expense, 
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