4 Mr . Ivory on the Method of computing 
disposition of the land and water on the same surface. Besides 
all this, after a long discussion, in which every circumstance 
that can affect the question, has been duly weighed, it seems 
now to be ascertained, that the elliptical figure of the earth, 
cannot be reconciled with the actual measurements which have 
been made for the express purpose of bringing the theory to 
the test of experiment. The hypothesis of Newton is there- 
fore not exactly consonant to observation : and we must infer 
that the solid part of the earth is not, at least in the present 
state of the globe, possessed of that regularity of figure, 
nor of that peculiar disposition of the internal strata, which 
would arise from the earth’s having been originally fluid. 
Hence it becomes necessary to consider the question of the 
figure of the planets in a more enlarged point of view ; to 
free it from all arbitrary suppositions, and to attempt such a 
solution of the problem, as shall apply to whatever figure or 
hypothesis may appear most agreeable to observation. It is in 
this way only, that theory and observation can mutually 
assist one another, and ultimately lead us to the truth — that 
theory can prompt observation, and observation perfect and 
confirm theory. 
The celebrated French mathematician, D’Alembert, was 
the first who contemplated the question of the figure of the 
planets in a general manner, by extending his researches to 
other figures than the elliptical spheroid. The difficulty is to 
investigate the attractive force of a body of any proposed 
figure, and composed of strata that vary in their densities, 
according to any given law. D’Alembert invented a method 
for this purpose which, although it is very ingenious, and so 
general as to apply in a great variety of cases, is nevertheless 
