IV. Of the Solids of Greatest Attraction, or those 

 which, among all the Solids that have certain Properties, 

 Attract with the greatest Force in a given Direction. By 

 John Playfair, F. R. S. Lond. and Edin. and Prof essor of 

 Natural Philosophy in the University of Edinburgh. 



\_Read 5th January 1807 •] ' 



I^HE inveftigations which I have at prefent the honour of 

 . fubmitting to the Royal Society, were fuggefted by the 

 experiments which have been made of late years concerning 

 the gravitation of terreftrial bodies, firfl, by Dr Maskelyne, 

 on the Attraction of Mountains, and afterwards by Mr Caven- 

 dish, on the Attraction ©f Leaden Balls. 



In reflecting on thefe experiments, a queftion naturally 

 enough occurred, what figure ought a given mafs of matter to 

 have, in order that it may attract a particle in a given direc- 

 tion, with the greateft force poflible ? This feemed an inquiry 

 not of mere curiolity, but one that might be of ufe in the fur~ 

 ther profecution of fuch experiments as are now referred to. 

 On conlidering the queflion more nearly, I foon found, though 

 it belongs to a clafs of problems of confiderable difficulty, 

 which the Calculus Variationum is ufually employed to re- 

 folve, that it neverthelefs admits of an eafy folution, and one 

 leading to refults of remarkable fimplicity, fuch as may intereft 



Vol. VI.— P. II. A a Mathematicians 



