1 
432 Mr. atwood’s ‘Theory for the Menfuration 
the index fhall point to feme degree near to 1 8o°, which is 
done by making that inclination very little more than one- 
fourth of the angle to be obferved, 
33. The tables 1. and 11. are calculated for taking the 
diameters of the fun and planets : the conftrudtion being formed 
on the principles which have been explained (art. 16. 17. 18, 
31. 32. fig. 12. 13-)' The fixed plane of reflection is coinci- 
dent with the primitive fecondary, and confequently n~ o • 
the common inclination of the refledtors to the plane of mo- 
tion = 10' ; and the conftant angle of incidence on the fixed 
fpeculum = 7 b 
TABLE I. 
Arc 
pointed to 
by the 
index. 
Obferved 
angle. 
Diff. 
i° 
/ // /// 
O 20 47 
it it/ 
20 47 
2° 
0 41 34 
20 47 
3 ° 
£ 2 21 
20 47 
4 ° 
i 23 8 
20 46 
5 ° 
i 43 54 
20 46 
6° 
2 4 40 
20 45 
7 ° 
2 25 25 
20 45 
1 8° 
2 46 10 
20 44 
j 9 ° 
3 6 54 
20 43 
0 
O 
w 
3 2 7 37 
TABLE II. 
Arc 
pointed to 
by the 
index. 
Ubierved 
angle. 
Diff. 
/ // /// 
3 ° 3 2 5 l 
IOO° 
it tt/ 
13 28 
IOI° 
3° 46 19 
13 20 
102 ° 
30 59 39 
13 12 
I° 3 ° 
3 1 12 5 1 
13 3 
104° 
3 1 25 54 
12 54 
105° 
3 1 3 8 4 8 
12 46 
106 0 
31 51 34 
12 37 
HH 
O 
0 
32 4 11 
12 28 
O 
00 
0 
32 16 39 
12 19 
iog° 
32 28 58 
12 11 
I IO° 
32 41 9 
The 
