on # 
‘-* 
# 
ee 
C. A. Schott on Magnetic Declination. 337 
= 
Formule expressing the secular change of the magnetic declination (commonly called 
‘Variation of the magnetic needle) used for calculating the tabular values.— Group 
1. Stations betwe. en Portland, Me., and Williamsburs 
A positive sign = Di indicates Pay declination, a negative een, east declination. 
"equals the number of years (and fraction of a year) from 1830; positive for 
Years after and. negative for years before this epoch. Soagitalis ‘are reckoned 
from Greenwich. 
Locality, Lat. |Long. | 
1 Burlington, Vt, fess 10] D==411'55 — 4°10 cos (1° songs i +390) 
Portland, Me. 43 3970 16 D=+10- 70— 2: 68 ont: as ot F ) 
R oat 
signed, Vt. = (43.86.72 55|D=+ 9 398-66 oo8 (1-5 
Cambridge, Mass. |42 9371 07/D=+- 9°65—2°78 cos (1° ES 22 cos 
in-+220°) 
5 Newburyport, Ms./42 48.70 49|D—=+ 9:55—2°56 cos(1'4 
7 |Boston, 42 2071 02|D=+ 9:16-2:55 cos (1° Som) 4092 oe | 
| S\Providence, R. 1. 41 5071 24|D=+4 911-2990 (1 Aon f09) E00 om 
10 Now ord, Conn. |41 4672 40|/D=+- 8'60—3°59 co (1 : Bee 
| atm daven, Conn, 411772 55|D=+4 8°13—3'49 cos (1°33n+-39) 
bany, N, 42 8973 43|D=+ 7°65—2°74 cos (1-42nF 62) 
ive .N. Y 42 27.75 42|D=+ 6°65 pone ried ih 
4 pee work, 40 4874 00\D=+ 6°47 vary pa 
15 Baaelphia, 39 58.75 10|D=+ 5:37 8-44 c08 (I'6n-+39), Loy 
»Pa. = 140 07/75 08|D=+ 5:28 ra e347?) 
2°10 — 2°25 rhe ‘bn+49) 
0 pot oe tis n-+-49) 
6 |Baltim, 
391 
nt Washington, D. C38 53/7 renin 
<lWilliamsburg, Va|97 15/76 40|D=+ 2:22—2°6 cos 
The followin table ber (n) of observations 
contains the number (n 
ingle or combined) upon which _— formula is based; the 
or (E expressed in minutes, as 
uracy with which the observations 
re Tepresented ; the epoch of the last minimum of west decli- 
r of maximum east declination) together with the least 
West rene tlination (greatest e east), and aga the annual variation 
“COND SERIES, y. t. XXIX, No. 87.—MAY, 1 
