102 Dip and Variation of the Magnetic Needle. 
Adopting for the central position, latitude 40° 57’ N., longitude 
4° 1)’ W., we obtain 0=3.31612, e=+.014728, y= —.000735, 
the dinates of the isoclinal line is from S$. 87° 8’ W. to N. 87° 
8’ E.; and the increase of dip in the normal direction is 53/088 
for sixty geographical miles. 'The mean of the differences at the 
eleven most northern stations is + 0/.6, at the twelve most south- 
ern + 0/.6, at the five most eastern stations: — 0’.2, at the six most 
western —2/.1, at the twelve intermediate +141. Hight of these 
differences exceed ten minutes. “F 
TaBie 1V.—Observations of i Brs.tatid id et 86° to 91° aest longitude. 
it Res BUS eee Sek... Weameower ewe Oe zt 
7 Statie Sy Lat. Lat. ) Con. ip |. Date Sarai Difi. 
Locke, +14, 
(Prose Locke and Loomis, |+23 | 
» | Pro’ - 9) 
Profs, ee ‘and Loomis, i Bi 
Profs shock and Loo 8 
y 8 e mis,/—"3 
Prof. Loo +1; 
23 | Prof. pore =.0 
Bay ee +5, 
23. ; 14 oe he ae «gta 
13 | |Prof. Loomis, pee 
37 ‘|Prof. Lockey le 9! 
52 Hi i j= 14 
38/72 ¢ a; “1+ 6: 
57 43 a dO 
23 é “a i d | 
2172 § 
40 |72 & 
44 |72 4 
23 |72 14. 
972 23 
8\71 55. 
23/89 5171 51. 
35 189 36 171.13, 
) 30 89 43/71 4. 
19.90 14/70 £ 
44/90 14 |70 ¢ 
23 190 50/69 & 
4189 53 69 < 
57|90 5|69 : 
55/90 3169 4 
54/90 4 344 
50/89 53169 57 - 
43 87 29 69 52. 
37 |90 4 69 28 
35 '86 25 69 35. 
23 |87 30|69 22 | 
“11 874869 5. 
59 |87 47 '68 56 .3 
_ Adopting for the central sata latitude af a N., longite , - : 
89° 47’ W., we obtain 3=3. ee 2=-+0.015972, y=+0.00 
twenty most northerly stations. is bavi de ; 
* é Pes Shee Baw hae 
