Variation and Dip of the Magnetic Needle. 207 
Dr. H. H. Sherwood, of New York city, has politely furnished 
me with several statements of the declination in different parts of 
the country, which are also incorporated in the table. 
Besides the preceding, I have been furnished with various 
additional observations, by the kind assistance of Mr. E. C. Her- 
rick, of New Haven. Some of these are extracted from “ Long’s 
Expedition & to the Rocky Mountains,” and “ Long’s Expedition 
to the Source of St. Peter’s River.” These are all to be found in 
our general table, and need not be repeated here. The remain- 
ing observations are as follows: Mr. Jedediah Herrick, of Hamp- 
den, Penobscot county, Maine, in a letter of April, 1837, says: 
“Thirty-two years ago, I found the declination at this place, 
by an ordinary semicircle, 114° W., and, during the past month, 
have made a series of observations with a better instrument and 
much care. Declination 13° 4’W. In 1825, at the Forks of the 
Penobscot, lat. 45° 30’, found the declination 14° 45’ W.” 
An almanac, by Nathan Wilde, for 1836, published at Keene, 
N. H., contains the declination of the needle for each year, from 
1812 to 1836. The observations were made by Mr. Wilde with 
a needle two feet long, at Chesterfield, lat. 42° 53’, long. 72° 20’. 
They are all shown in our table. In June, 1837, the variation at 
the same place was determined, by Mr. A. C. Twining, to be 8° 5’ 
The variation at Barton, Vt., was determined July 8, 1837, in 
the evening, at 10° 51/ W., by Mr. Twining; and at St. Johns- 
bury, July 22, 1837, at 11 P. M., 9° 16’ W. 
At Burlington, Vt., the variation is stated by Prof. Benedict at 
9° 45/, or 9° 50 
The Gazette and Merenry, published at Greenfield, Mass., Dec. 
19, 1837, states: ‘It has recently been determined in Sesrhetd. 
, by a number of observations with accurate instruments, 
that the variation of the needle is at present 7° 57’ W.” 
At New York city, about three years ago, the variation was 4° 
50’ W., as stated by Mr. W. C. Redfield. 
Mr. G. C. Schaeffer, of New York city, states that Prof. Ren- 
wick, of Columbia College, determined the magnetic variation in 
the summer of 1837 at Constable’s Point, about five miles S. W. 
of the City Hall, under favorable circumstances, being on a sandy 
ee far away ‘from local attraction. - Variation, 5° 40’ W. 
At Philadelphia, Sept. 1837, variation 3° 52’ W., as stated by 
Mr. Walter R. Johnson. 
Vor. XXXIV.—No. 2. 38 
