-176 "Mr. VlNCE 071 the Motion of 



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

 the nature of the experiments which have been made by 

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

 were conclufive in refpe(fl to the principles which have been 

 deduced from them. The experiments which have been made 

 by all the authors that I have feen, have been thus inftitutedr 

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

 ♦motion : and they concluded from thence, that the accelerative 

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

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

 than the force which oppofesits motion, otherwife it could not 

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

 this, it is evident, that the fri6lion could not be very accurately 

 obtained ; but there is ancHrher obje£tion which totally deftroys 

 the experiment fo 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 'I2i 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 which cafe the frldion 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 wou^ put 

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

 upon the plane at reft, acquired a very ftrong cohefion to it. 

 idly, 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. 

 ^'ould juft put it in motion ; but that a moving force of 4 oz. 



wouIJ 



