C. A. Schotti— Magnetic Declination in the United States. 27 
the theodolite and magnetometer, from the circumstance that 
the various observations for the same nominal locality were 
taken at different spots, oe changes of local deflections of 
the magnet. From the extended use of iron and the growth of 
cities, it is difficult to siden’ a preserve in such places a suitable 
locality for use at future shee a investigations of the 
secular change can onl made at permanent observatories, 
or in localities not liable to dating influences. 
n applying a periodic function to the ath bes of the 
secular change, it is not implied that the phenomenon is neces- 
sarily of a periodic character, or must exhibit more ibad a single 
complete period ; the aim is to represent by such a function the 
sat in the direction of the magnetic resultant, as far as 
The blleotich of the material is given first, the ee being 
arranged in geographical order, beginning in the northeast, 
me to the south and west, and ending in the mouth woast 
or each locality the observed declinations are given in chrono- 
logical order, together with such notes and references, respecting 
observer, place, publication, ete., as could found. The 
stations here given are the onl ‘ones at present suitable for a 
“aaees of the secular change, but their number is constantly 
increasing by the accumulation of new facts. [The collection 
referred to is here omitted. 
The following table contains the empirical expressions for the 
magnetic declinations derived from the collected observations 
by ithe process explained above, for various localities, together 
with their latitudes and longitudes. Total number of stations, 
43, and of observations, about 4 
TaBLe I. 
Locality. Latitude |Longitude Expression of Magnetic Declination. 
Halifax, N. 8. £4 39°6| 63 35-3|D=+15°94+ 4°42 sin (1°0 m+ 49°2) 
uebec, Can. 46 48-4) 71 14°5|D=+12°67+ 3°84 sin (1°65m+ 43°6) 
York Factory, Hud. Bay. 57 00° | 92 26° |[D=+ 5°08 +1412 sin (16. m— 79-4) 
Portland, Me. 43 38°8| 70 16°6|/D=+10°72+ 2°68 sin (1°33m+ 24°1) 
Burlington, Vt. 44 28-2) 73 12°3/D=+11:16+ 3:76 sin (1°30m— 26° 
18 sin (7-2m+ 138) 
Rutland, Vt, 43 365) 72 55°5|D=+ 976+ 3°64 sin (1°6 m— 19°6) 
ally N. H. 43 04°8) 70 43-0 patie 29+ 2°56 sin (1°37m+ 5°9) 
Saetyport Mass. 42 48-4 70 49:0/D—+ 9°63+ 2°63 sin (1-4 m+ 13°2) 
42 31-9| 70 52°5|D=+1022+4 4°04 sin (1°55m— " 
a, Mas 42 21°5| 71 03°8/D=+ 9.46+ 2°83 sin(l'3 m+ 46 
Cambridge, iia 42 22°9| 71 07°7|/D= + 958+ 2°69 sin (13 m+ 7-0) 
ei + 0°18 sin 1 (2°2m + 44) 
* This approximates to an arrangement proceeding from the anaied western 
to the greatest eastern declinations. 
