the mean Denjity of the Earth. 
765 
16. Depreflions below ? in the S.E. quarter. 
Rmgs.| I i 2 r 3 I 4 I 5 1 6 1 7 I 8 r j j 10 1 11 I I- 2 l Rad ' r 
£ O 
20 I 30 i 3° 1 1 1 1 I L 
abo | ago] 290 | 280 | 240 | 1 50 j 30 I |_ 
420 j 440 I 450 I 440 1 420 | 370 I 270 I.140 | 
JJoJ 
I 210 I 
4333 
5000 
270 | 
. 3.5 
5667 
6333 
1 1 
I 2 
13 
14 
1 5 
16 
17 
18 
l 9 
8 33 3 
9000 
530 1 54 Q I 5 6 ° I 5 6 ° 1 . 55 ° i 48 o 1 430 i 330 1 15 ° ] 40 I 40 I 43 ° [ 7000 
500 j 510 | 520 j 550 | 630 | 600 | 300 [430 | 290 J 23O ] 200 [ 630 | 7667. 
4 50 I 430 1 420 I 410 1 43 ° 1 57 ° I 6 3 ° I 53 Q I 430 i 480" j 3 4 0 [ 7 10 j 
360 I 330 1 3 ‘Q I 2 9 ° I 280 i 330 I 5 1 o j 670 1 590 I 630 1 570 1 830 1 
24O | 23O j 220 | 200 j l8o [ 200 [ 33O | 530' 1 770 1 760 j 710 | 870-f 
180 | 160 | 150I 1 30 | 1 so 1 14H 23? | 3301^301830! 79 ° 1 g 8° I 10 33 3 
1 10 | 80 | 50 | 40 | 30 | 90 I 1 90 I 280 I 500 I 860 I &30i 860 1 1 1000 
1 50 | 60 ], 4-00 | 760 I 830,1 760 (11667 
10 
10 
J 70 1 230 1 330 [600 1 770 1 630 112333 
20 
10 1 180 1 290} 530 [690 1 533 1 1 300c 
It remains now to find the fines of the- vertical angles 
fubtended by all the foregoing altitudes and depreflions, 
fince the fum of thefe fines is what we are in quell of. 
Each altitude or depreffion is the perpendicular of, a 
right-angled triangle, of which the given radius Handing 
on the fame line with it in the right-hand margin is the 
bafe, or other fide about the right-angle; and by the rer 
folution of the right-angled triangle, for each perpendi- 
cular, the fame number of correfponding fines will be 
found. But with fuch data the tangent of the angle is 
much eafier to be found than the fine, and the analogy 
for that purpofe is this, as the bafe : to the perpendicu*- 
lar : : I (radius) : the tangent required, which will there- 
fore. 
