1 2 Mr, L an den’s ‘Wv^igadwnidf 
that a -ci one, a conoid, a pnfm , or a pyramid , &c. of certain 
d intentions, will have the like property of continuing, with- 
out any reftraint, to revolve about any axis palling through its 
center of gravity. 
When the axis, about which a body may be made to 
i evolve, is not a permanent one, the centrifugal force of its 
particles will difburb its rotatory motion, fo as to caufe it to 
change its axis of rotation (and confequently its poles) every 
inftant, and endeavour to revolve about a new one : and I can- 
not think it will be deemed an uninterefting proportion to de- 
termine in what track, and at what rate, the poles of fuch 
momentary axis will be varied in any body whatever; as, 
without the knowledge to be obtained from the folution of 
fuch problem, we cannot be certain whether the earth, or any 
other planet, may not, from the inertia of its own par- 
-'ti-^les, fo change its momentary axis, that the poles thereof 
(hall approach nearer and nearer to the prefent equator, or 
whether the evagation of the momentary poles, arifing from 
that caufe, will not be limited by forne known lefler circle. 
Which certainly is an important confideration in aftronomy ; 
efpecially now that branch of fcience is carried to great per- 
fection, and the acute aftronomer endeavours to determine the 
motions of the heavenly bodies with the greateft exadtnefs 
pcffible. 
I do not know that the problem has before been folved by 
any mathematician in thefe kingdoms; but I am aware that it 
has been conlidered by fome gentlemen, very eminent for their 
mathematical knowledge, in other nations. The folutions of 
it, given by the celebrated M. Leonhard Euler and M. 
D’Alembert, I have been: and we learn from what' 'the. laft 
mentioned gentleman has faid, in his Gpujculcs iAat hematiques , 
that 
