ABRASION OF THE SURFACES OF SOLIDS. 



151 



Remarks. 



1. That with fibrous substances, such as cloth, friction diminishes with an increase of weight. 



2. That friction is greater (cseteris paribus) with fine cloths than with coarse cloths. 



3. That friction is greatly increased by time. 



4. That friction varies from one-third to an amount greater than the total weight. 



Table II. Experiments on the Velocities with Drab Milled Kerseymere, No. 3. 



Weight on 

 surface. 



lbs. 

 1 



5 

 10 



20 



Weight required 

 to move it. 



Total space 

 passed over. 



Time in seconds. 



Remarks. 



Of 9 square inches surface. 



lbs. oz. 

 1 8 



1 5 



2 5 

 2 6 



4 3 



6 7 

 9 7 



1 



inches. 

 24 



halfway in 17 sec. the whole in 

 17 

 21 

 33 

 17 

 29 

 45 

 30 



mean of 3 trials 



45 



32 



30 



22 



23 



24 



25 



40 



37 ' 



31 



26 



27 



30* 



53 



30* 



45 



63 



50 



From lib. toSlbs. the adhesion 

 is greater than the weight on 

 surface. 



Velocities very irregular. 



Velocities very irregular. 



* Denote the experiments that 

 approximate the nearest to an 

 uniform velocity. 



Results very irregular, owing 

 perhaps to the fibres of the 

 cloth having been previously 

 compressed. 



lbs. 

 20 



20 



Of 18 square inches surface. 



lbs. oz. 

 13 6 



after remains 14 hr3.> j^q « 

 it took to start it f *o a 



inches, 

 mean of 3 trials 31 



1st half. 2nd half. 

 22 33 



Increase of surface shows an 

 increase of resistance with 

 equal weights of 20Ibs. 



Time nearly doubles the resist- 

 ance. 



Of 27 square inches surface. 



lbs. 

 1 

 2 

 5 



10 



lbs. 

 2 

 3 

 6 



10 



oz. 



8 



10 



7 

 2 



inches, 

 mean of 3 trials 18 



1st half. 2nd half. 



4 14 



30 73 



25 60 



28 55 



Three times the surface nearly 

 three times the resistance.— 

 Velocities irregular. Vide 

 Vince's Experiments. 



Nearly uniform. 



1. From the foregoing experiments it appears that velocities observe no particular law, except in 

 three instances, where the last halves of the space passed over approximate to the first halves. 



2. That increase of surface very much increases the resistance. 



