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XV, Anew 'theory of the Rotatory Motion of Bodies affeBed 
by Forces dijlurbing fuch Motion. By Mr. John Lan- 
den, F. R. S. 
Read Feb. 20, T am induced to conlider this paper as 
1777. 1 
not unwoithy the notice of this Society,, 
through a perfuafion that the theory herein contained 
will conduce to the improvement of fcience, by enabling 
the reader to form a true idea, and accordingly to make 
a computation of the motion (or change) of the axis about 
which a body having a rotatory motion will turn, or have 
a tendency to turn, upon being affeCted by a force dif- 
■ ■y' . * 
turbing its rotation; particulai'ly of the motion of the 
earth’s axis arifing from the attraction of the Sun and 
Moon on the protuberant matter of the earth above its 
greateffc infcribed fphere: which compound motion* I 
conceive, has not been rightly explained by any one of 
the eminent mathematicians whofe writings on the fame 
fubjeft have come to my hands. Whether in this elfay 
I have really fucceeded better than other writers who 
have attempted an explanation of fuch motion, I fubmit 
to gentlemen well verfed in mechanics to determine. 
1. Fig. 
