24 Rev. O. Fisher on Deflewions 
the excess of the density of the substratum over that of the 
erust, and the attraction of the root ML RC at P will be 
the same as would be produced by a mass K LR CB minus 
that which would be produced by a mass K MC B, each mass 
being of similar density. Consequently we need to calculate 
these several attractions. The attraction having been calcu- 
lated from the formule, the corresponding deflexion may 
be found by multiplying it by a factor whose logarithm is 
0°3541084 *. 
Attraction a+ p cos 22) tan> (= tan a 
of the slope =2p4 (ut ie ct pp 
a(a+ 2p cox? a) 
“sin @ cos 2 log ilieer - 
p? cos? a 
ha ae 
20(3*3) 
‘The upper or lower sign is to be used according as the 
attracted particle P is to ihe right or left of the foun of the 
slope under consideration. 
nels 
ae 
Attraction a 7 { tan th | slog pial eel thy + const. 
the plateau ey—l ~ lee 2: a 
The limits of # are the nearest and furthest distances of 
‘the base of the plateau from the station P, viz. PD and 
PD+400. 
v= V2+h2+ 22 and its limits depend upon those of «. 
The unit of length is a mile. 
21 is the length of the range=880. 
(1) When the attraction of the slope HDA is required : 
p— 200. 
a= WAS 124 ilies ie 
k=3°3 miles, 
i peel Dees 
oo DA ae 
[=440. 
p is the distance from the foot of the slope A of the 
station where the attraction is required. 
* See Clarke’s ‘ Geodesy,’ p. 296. 
+ Observe: In the Addendum DA is taken at 95 miles. 
