288 Mr. lan den’s new theory of 
3 denoting half the length of the cylinder, and r the 
radius of any fedtion at right angles to its proper axis. 
Seeing that ) the expreffion for the faid 
accelerative force refpedting the cylinder vanifhes when b 
i 
is = it is manifeft that the cylinder in that cafe will 
(with refpedt to its own particles) undifturbedly revolve 
about any axis whatever paffing through its center of 
gravity, as will a fphere. Which remarkable property of 
that particular cylinder I believe has not before been 
taken notice of. 
There are, I am aware, bodies of other forms having 
-the like property. 
The preceding articles lead us to confider the motion 
of the earth’s axis in a light, I prefume,, more clear and 
fatisfadtory than any in which it has before been confi- 
.dered ; hut I muft, for want of leifure, defer making the 
application till fome future opportunity ; only obferving 
here, that by what is done above it appears, that from 
the adtion of the Sun and Moon on the earth its axis has 
a diurnal motion, which I have no where feen explained. 
Which motion is not much unlike that of the axis of 
the revolving fpheroid juft now confidered, when (2 b) 
this laft mentioned axis is many times longer than (af) 
a the 
