£ 689 ] 
XXXIII. An Account of the Calculations made from the 
Survey and Meafures taken at Schehallien, in order to 
afcertain the mean Denjity of the Earth. By Charles 
Hutton, Efq. F. R. S. 
Read May 21, r g ‘'HE furvey from which thefe calcula- 
>778. I 
tions have been made was taken at and 
about the hill Schehallien in Perth fir ire, in the years 
1774, 1 77 5> and 1 7 7 6, by the direction, and partly un- 
der the infpedtion, of the Rev. nevil maskelyne, d. d. 
f. r. s. and Aftronomer Royal, by whom the manner of 
making the furvey has ahead y been fully explained in 
the Philofophical Tranfadtions for 1775. 
I have therefore only to give an account of the mea- 
fures of the lines and angles, and of the calculations 
which I have raifed from them with all poffible care and 
faithfulnefs, for the purpofe of determining the meafure 
of the ratio of the mean denllty of the earth to that of 
water or any other known matter. 
Thefe calculations were naturally and unavoidably 
long and tedious ; and the more fo as the bulinefs was in 
a manner quite new, which laid me under the neceffitv 
Vox, LXVIII. * 4 Q of 
