1-6 'Mr. ViNCE on the 'Motion of 



before I conclude, to give the refult of my examination mto 

 the nature of the experiments which have been made by- 

 others ; wliich were repeated, in order to fee how far they 

 were conclufive ill refpe6t to the principles which have been 

 .deduced fromthem. The experiments which have been made 

 by all the authors that I have (t^n^ have been thus inftituted. 

 To find what moving force would juft put a body at reft in 

 motion : and they concluded from thence, that the accelerative 

 force was then equal to the friction ; but it is manifeft, that 

 any force which will put a body in motion muft be greater 

 til an the force which oppofes its motion, otherwife it could not 

 overcome it ; and hence, if there were no other objeiStion than 

 this, it is evident, that the fridtion could not be very accurately 

 obtained ; but there is another objedion which totally deftroys 

 the experiment lb far as it tends to fhow the quantity of fric- 

 tion, which is the ftrong cohefion of the body to the plane 

 when it lies at reft; and this is confirmed by the following 

 experiments, ift', A body of 12| oz. was laid upon an hori- 

 zontal plane, and then loaded with a weight of 8 lb. and fuch 

 a moving force was applied as would, when the body was juft 

 put in motion, continue that motion without any acceleration, 

 in whi(^h cafe the fridlion muft be juft equal to the accelerative 

 force. The body was then ftopped, when it appeared, that the fame 

 moving force which had kept the body in motion before, would 

 not put "it in motion, and it was found neceflary to take off- 

 4I oz. from the body before the fame moving force wouU pxit^ 

 it in motion "; it appears, therefore, that this body, when laid 

 "Upon the plane at reft, acquired a very ftrong cohefion to it, 

 ~2dly, A body whofe weight was 1 6 oz. was laid at reft upon the 

 horizontal plane, and it was found that a moving force of 6 oz, 

 vB^ouldjuft put It in motion; but that a moving force of 4 oz, 



would 



