[ 533 1 
preach, to its centre, the attradlion thereof mnft have 
been wholly infenlible. But now, by only fuppoiing the 
mean deiihty of the earth to be double to that of the hillj 
which feems very probable from other conliderations, 
the attraction of the hill v/ill be reconciled to the gene- 
ral law of the variation of attraction in the inverfe du- 
plicate ratio of the diifances, as deduced by Sir Isaac 
NEWTON from the comparifon of the motion of the hea- 
venly bodies with the force of gravity at the furface of 
the earth; and the analogy of nature will be preferved. 
3. We may now, therefore, be allowed to admit this 
law; and to acknowledge, that the mean denlity of the 
earth is at lead: double of that at the furface, and confe-' 
quently, that the denlity of the internal parts of the earth. 
is much greater than near the furface. Hence alfo, the 
whole quantity of matter in the earth will be at lead: as 
great again as if it had been all compofed of matter of 
the fame denlity with that at the furface; or will be 
about four or five times as great as if it were all com- 
pofed of water. The idea thus afforded us, from this 
experiment, of the great denlity of the internal parts of 
the earth, is totally contrary to the hypotheffs of fome 
naturalifts, wdio fuppofe the earth to be only a great hol- 
low fhell of matter; fupporting itfelf from the property 
of an arch, with an immenfe vacuity in the midd: of it. 
But, were that the cafe, the attraction of mountains, and 
-even fmaller inequalities in the earth’s furface, would be 
very, great, contrary to experiment, and would affeeff the 
meafures 
