Boiiies iijfl'tteci by Fricficn, I '^« i 



, . . Qiiantity of fiii^ion i -.-it. 



retardation vanes as -^ — ~ — 7: ; hence, it a body be r>ut 



Quantity ot matter ' / r *• 



ill motion npon the horizontal plane by any moving force, if 

 both the weight of the body and the moving force be increafed 

 in the fame ratio, the acceleration ariling from that moving 

 force will remain the fame, becaufe the accelerative force varies 

 as the moving force divided by the whole quantity of matter, 

 and both are increafed in the fame ratio ; and if the quantity 

 of fri£^ion increafes alio as the weight, then the retardation 

 arifing from the fri6lion will, from what has been faid, remain 

 the fame, and therefore the whole acceleration of the body will 

 not be altered ; confequently the body ought, upon this fuppo- 

 iitlon, fliill to defcrlbe the famefpace in the fame time. Hence, 

 by obferving the fpaces defcribed in the fame time, when both 

 the body and the moving force are increafed in the fame ratio, 

 we may determine whether the fri6lion increafes in proportion 

 to the weight. The following experiments were therefore 

 made in order to afcertain this matter. 



Exp. I. A body weighing 10 oz. by a moving force of 4 oz. 

 defcribed in 2^^ a fpace of 5 1 inches ; by loading the body with 

 10 oz. and the moving force with 4 oz. it defcribed ^6 inches 

 in 2"; and by loading the body again with 10 oz. and the 

 moving force with 4 oz. it defcribed 61 inches in 2^\ 



Exp. 2. A body, whofe weight was 16 oz. by a moving 

 force of 5 oz. defcribed a fpace of 49 inches in 3'^; and by 

 loading the body with 64 oz. and the moving force with 20 oz. 

 the fpace defcribed in the fame time was 64 inches. 



Exp. 3. A body weighing 6 oz. by a moving force of 2| oz., 

 defcribed 28 inches in 2'^ \ and by loading the body with 24 

 oz. and the moving force with 10 oz. the fpace defcribed in the 

 fame time was 54 inches. 



Z 2 Exp. 



