30 On llie Motion of Bodies ([Reeled ly. Friction. 



3" : ihc stage was then adjusted to the space corresponding 

 to 2", upon supposition tlint the spaces descended through 

 were as tlie squares oi: the times ; and it was found to ;igree 

 accurately with tlie time : tl^e stage was then adjusted to the 

 space corresponding to l", upon the same supposition j and 

 it was found to agiec with the time. 



Exr. 3. A third hodv was laid upon the horizontal plane, 

 and a niovinsi' force appiietl, which descended 5()j inches in 

 a" -. the stage was then adjusted to the spaet corresponding 

 to 3", upon supposition that the spaces descended throuoh 

 were as the sejuares of the times, and it was found to agree 

 with the time : the stage was then adjusted to the' space cor- 

 responding to '2", upon the san)e supposition, and it was 

 found to agree with the time: the stage was then adjusted 

 to the space corresponding to l", and was found to agree 

 ^\ith the tmie. 



Exp. 4. A fourth l)ody was then taken and laid upon tiie 

 horizontal plane, and a moving force applied, which de- 

 scended 53 inches in 4" : the stage was then adjusted to the 

 space through which it ought to descend in 3", upon sup- 

 position that the spaces descended through were as the 

 squares of the times, and it was found to agree with the 

 time : the stage was then adjusted to the space corresponding 

 to 2", upon the same supposition, and was found to agree 

 with the time: lastly, the stage was adjusted to the space 

 corresponding to l", and it was found to agree exactly with 

 the time. 



Besides these experiments, a great mmiher of otliers were 

 made w itli hard hodies, or those whose parts so firmly co- 

 hered as not to be moved inter se by the friction ; and in 

 fach experiment bodies of very difterent degrees of friction 

 were chosen, and the results all agreed with those related 

 above : we may therefore conclude that the friction i>f' lidrd 

 todies in niolivn is an iitiiformltj retarding force. 



tjul to determine whether the same was true for bodies" 

 when covered with cloth, woollen, &.e. experiments were 

 made in order to ascertain it; when it was found in all 

 cases, that the retarding force increased with the velocity; 

 but, upon covering bodies with paper, the consequences 

 were found to agree with those related above. 



4. Having proved that the retarding force of all hard 

 bodies arising from friction is uniform, the ipiantitv of fric- 

 tion, CQnsidt;red as equivalent to a wciglit without inertia 

 drawing the body on the horizontal plane !)aekwards, or 

 acting contran' to llie moving force, may be innnedialely 

 deduced from the foregoing experiments. For let M = the 



mcivina: 



