154 



PHYSICAL GEOGRAPHY. 



declination of a place, when it is possible to detemiine that declination 

 by a direct observation upon the true meridian. 



By the general direction of these lines in New England, it appears 

 that, by moving north-westerly or south-easterly, but little change will 

 be noted in the declination; but in going north or north-east it will 

 increase, and diminish in going south or south-west. The followiiig 

 declinations were observed by Dr. T. C. Hilgard, for the United States 

 Coast Survey, in 1873: 



Station. Date. Declination. 



Gorham, Sept. 8-1 1, 12° 42' 



Uttleton, Sept. 22-25, '3 47' 



Hanover, Oct. 2-6, 10° 47 * 



Hanover, Oct. 8-1 1, 10=50'* 



Burlington, Vt., Oct. 12-15, 11° 22' 



Rutland, Vt., Oct. 17,18, 10° 40' 



By observations made by Rev. C. A. Downs, of Lebanon, the declina- 

 tion at that place is 11° 30/. 



The following declinations are copied from previous observations by 

 the United States Coast Survey: 



Station. Date. Declination. 



Burlington, Vt., 1855— Aug. 28, 9° S7'.i 



Mt. Agamenticus, Me., 1847— Sept. 23-Oct. 2, 10° og'.S 



Mt. Patuccawa, 1849— Aug. 1S-19. i°° 42'.8 



Mt. Uncanoonuc, 1848— Oct. 6-8, 9° 04'.! 



Isle of Shoals, 1847— Aug. 12-19, ^°° °3'-S 



Plum Island, Mass., 1850— Sept. 18-20, 10° 05'.6 



2. Secular Variation of the Declination. The line of no declination 

 and the other isogenic lines are not fixed in position, but are slowly mov- 

 ing. This motion, in the United States, is at the present time for the 

 most part toward the south-west. In 1801 the line of no declination 

 passed nearly through Annapolis, Md., crossing Lake Erie about forty 

 miles from Buffalo. In 1850 it had gone to the west upon our coast as far 

 as Beaufort, N. C, and, passing west of Pittsburgh, Penn., crossed Lake 

 Erie near its centre. In 1 870 it passed very nearly through the cities of 

 Raleigh, N. C, and Cleveland, O. At the present time, the declination is 

 more than 3" upon the line where, in 1801, it was 0°. The influence 

 which causes this change in declination is passing over this continent 

 from north-east to south-west, as will be seen by the following extract 

 from a report on secular changes in declination, &c., by C. A. Schott, 



* Probably too small on account of local attraction. 



