200 
Dr . Charles Hutton on 
of my Mathematical Tracts. It may there be seen, that 
after computing, trigonometrically, the bearing and distance 
of every point in the numerous sections of the mountain, 
from the two observatories, I conceived it to be divided into 
nearly one thousand vertical columns, of given bases and 
altitudes. I then computed the quantity of the attraction of 
all these columns, on the plummet, in the direction of the 
meridian, when placed at the two observatories, on both 
sides of the hill, where the whole effect had been observed, 
which attraction was thus found to be expressed by the 
number 88nf. I then computed, from the magnitude of 
the earth, what must be its attraction on the same plummet, 
and found it expressed by the number 87522720. 
Consequently, the whole attraction of the earth, is to the 
sum of the two contrary attractions of the mountain, as the 
number 87522720 to 881 if; that is, as 993 3 to 1 very 
nearly ; on supposition that the density of the matter in the 
hill, is equal to the mean density of that in the earth. 
But Dr. Maskelyne found by his observations, that the 
sum of the deviations of the plumb line, produced by the 
two contrary attractions, was 11.6 seconds. Hence then it 
is inferred, that the attraction of the earth, is actually to the 
sum of the attractions of the hill, nearly as radius to the 
tangent of 11.6 seconds, that is, as 1 to .000056239, or as 
17781 to 1 ; or as 17804 to 1 nearly, after allowing for the 
centrifugal force arising from the rotation of the earth about 
its axis. 
Having now obtained the two results, namely, that which 
arises from the actual observations, and that due to the com- 
putation on the supposition of an equal density in the two 
