Manchester Memoirs, Vol. liii. (1909), No. VX / 



60 as the distance of the moon in semi-diameters of the 

 earth in combination with the same even number in 

 seconds and minutes of time greatly facilitated the 

 demonstration of the law of the attraction of gravitation, 

 the truth of which could at once be perceived by a simple 

 mental calculation. Thus 60x60=3600 is the attractive 



force at the earth's surface, and reciprocally -^ at the 



3600 



distance of the moon's orbit. Now this same demonstra- 

 tion is equally applicable to the quantity of moving force 

 of terrestrial bodies as well as at the distance of the 

 moon's orbit. For as the moving force is as the square 

 of the velocity, a body falling during one minute through 

 a distance of 16 feet i inch at the moon's orbit, that is to 

 say, with a velocity 60 times less than at the earth's 

 surface, its moving force would be 60 X 60= 3600 times 

 less than that of a body falling the same distance during 

 one second of time on the terrestrial globe. Therefore 

 the moving force and the attraction of gravitation are 

 alike inversely proportional to the square of the distance, 

 and are correlated equally in amount to maintain and 

 retain the moon in its orbit during the course of its 

 revolution round the earth. 



14. The quantitative relations of the moving and 

 attractive forces of the planetary bodies are set forth in 

 the following new calculus of elements, wherein Mercury 

 is taken as unity instead of the Earth, as in ordinary 

 astronomical tables. 



15. The masses of the bodies are taken as equal and 

 require to be multiplied by the specific mass of each 

 planet for the total force. 



16. As the moving and attractive forces are 



