Bodies affected by VrlcllofU \^\ 



dChiantity of friftion < • .■* « t « 



ation vanes as ^ — 7-^—7 ; hence, it a bodv be put 



Quantity or matter ' / r ^ 



in motion upon 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 arifing from that moving 

 force will remain the fame, becaufe the accelerative force varies 

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

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

 of fri61:ion increafes alfo as the weight, then the retardation 

 arifmg from the fri£lion will, from what has been faid, remain 

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

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

 (itlon, ftill to defcribe the fame fpace 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 fridlion 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 i Inches ; by loading the body with 

 ID oz. and the moving force with 4 oz. it defcribed 56 inches 

 in z" \ and by loading the body again with 10 oz. and the 

 moving force with 4 oz. it defcribed 6 \ inches in z'\ 



Exp. 2. A bodv, whofe weight was 16 oz. by n moving 

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

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

 the fpace deicribed 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 z" ; and by Joading the body with 24 

 oz. and the moving force with 10 oz. tl;c fpace defcribed in the 

 fame time was 54 inches. 



Zr, F Y O 



