Variation and Dip of the Magtietic Needle. 297 



Dr. H, H. Sherwood, of New York city, has politely furnished 

 me with several statements of the dechnation 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, 11^° 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, Yt., the variat^.on is stated by Prof. Benedict at 

 9° 45', or 9° 50' W. 



The Gazette and Mercury, published at Greenfield, Mass., DeCi 

 19, 1837, states : " It has recently been determined in Deerfield, 

 Mass., 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 

 point, far away from local attraction. Variation, 5° 40' W. 



At Philadelphia, Sept. 1837, variation 3° 52' W., as stated by 

 Mr. Walter R. Johnson. 



YoL. XXXIY.— No. 2. 38 



