296 Vaiiation and Dip of the Magnetic Needle. 



in the Eastern States with which he was acquainted ; and in the 

 Memoirs of the American Philosophical Society, as well as in 

 those of the American Academy, various observations are recorded. 

 The substance of all of these is given in the general table which 

 follows. 



In the Aurora, a paper published at Philadelphia, July 27, 1813, 

 is a communication from David M'Clure, stating the variation in 

 Philadelphia at that time to be 2'^ 25' W. In the same paper for 

 Sept. 12th, is a communication from Thomas Whitney, mathe- 

 matical instrument maker, stating the following facts. It ap- 

 pears that the variation was here 8° 30' W. in 1710. In 1793, it 

 was observed by R. Brooks to be 1° 30' W. In 1804, it was ob- 

 served by several men of science to be 2° W. An anonymous 

 communication in the same Journal for Sept. 15th, states the va- 

 riation at Lewis, in Delaware, in 1795, to have been 55' west. 



The following facts I have learned from various sources. Mr. 

 N. Goodwin, surveyor in Hartford, Ct., determined the variation 

 at that place in 1824, to be 5° 45' W. ; in 1828, 6° 3' W. ; and 

 in 1829, 6° 3' W. He also determined the variation in New Ha- 

 ven for 1828 to be 5° 17' W. 



The variation at Pensacola, Florida, was stated to me in 1835, 

 by an officer of the navy, to be 6° E. 



The variation for New York is given at 4° 40' Vf. in 1824, 

 on Blunt's map of that year. 



The variation at New Haven is also given at 5° 10' W. in 1811, 

 on a map of that city. 



The variation at Montpelier, Vt., in 1829, was 12° 25' W., as 

 given in Executive Documents, Vol. IV, No. 190, page 23. 



Variation at Kaskaskia,'Ill., in 1809, 7° 20' E., according to 

 American State Papers — Public Lands, Vol. II, page 195. 



Variation at Alton, 111., was given me at 8° E. in 1835. 



Variation at Athens, Ga., in 1837, 4° 31' E., as determined by 

 Prof McCay. 



Variation at South Hanox'"er, Indiana, in 1837, 4° 35' E., as de- 

 termined by Prof Dunn. 



Variation at West Chester, Pa., in 1832, was 3° 25' W., as ob- 

 served by Prof Bache. 



The Annual Report of the Regents of the University of the 

 State of New York for 1837, contains the observations made at 

 eleven different places in the State. These are all to be found in 

 our general table. 



