TOTAL SOLAE ECLIPSE OE JULY 18, 1860. 
367 
and mth wires II. and IV. 
at an interval of 193'5 
„ „ 193 
Sum 386*5 
whence angle ^=44° 19'-5. 
h min. ^ ^ 
At 4 35 p.M. ip= 45 43*5 
At 11 55 A.M. <p= 44 19*5 
Interval 4 40 diff. + 1 24*0 
Interval . . . . = 280 =+ 84 
+ 84 
-^ = +0'*3 the change of the angle ^ in 1 minute. 
h m sec. 
No. 6 photograph was taken at ... . 1 47 48 
Deducting .... 1 1 55 0 
1 52 48 = 112-8 min. 
112*8 X 0'-3 = 34', 44° 19'*5 + 34'= 4° 53'*5, the position of wire I. in reference to a 
circle of R. A. at the epoch of No. 6 photograph ; hence the correction to be applied to 
the assumed position of 45° is — 6'*5. 
With the foregoing data has been calculated the following Table of corrections, to be 
applied to the assumed position of the wires at the epochs of the several photographs. 
No. 
Correction to 
the wires. 
No. 
Correction to 
the wires. 
No. 
Correction to 
the wires. 
6. 
— 6*5 
20. 
+ 9*5 
32. 
+ 23-2 
7. 
-5*1 
21. 
+ 11-0 
33. 
+ 25*4 
8. 
— 4-0 
22. 
+ 11*7 
35. 
+ 26-4 
9. 
-2-0 
23. 
+ 12-6 
36. 
+ 27*6 
10. 
-1*8 
24. 
+ 14-0 
37. 
+ 28-4 
1 1. 
-0*7 
25. 
+ 15-5 
39. 
+ 29*8 
12. 
+ 0‘5 
26. 
+ 16-3 
41. 
+ 31-9 
14. 
+ 3-2 
27. 
+ 18 
42. 
+ 33-0 
I 15. 
+ 4-0 
28. 
+ 19*4 
43. 
+ 33-9 
: 16. 
+ 5-3 
29. 
+ 20-3 
44. 
+ 35-3 
+ 7*1 
30. 
+ 21*2 
45. 
+ 37*0 
19. 
+ 8-0 
31. 
+ 22-5 
1 
In these corrections I have not taken into account a small error in the computed 
angle of <p, which arises in consequence of the wires not being at right angles ; for, on 
examining them, I found that the heat of the sun had caused a curvature in one, and I 
could not, without much trouble, have ascertained the correction with precision. It 
was computed that it would not, however, amount in any case to more than +2'. My 
measurements of position-angle, hereinafter given, are moreover liable, from the diffi- 
culty of adjusting the photographs, to discordances to the like extent, as will be easily 
3 D 2 
