ABRASION OF THE SURFACES OF SOLIDS, 



165 



REMARKS. — The irregularity of the resistances observed in the first seven experiments arose 

 from the impartial contact and consequent grinding or abrading of the surfaces. The roller having 

 attained its bearing, and the weight in the roller-scale being diminished, the irregularity ceased, 

 especially when oil and tallow were used. 



From the result of these experiments it will be seen, that friction did not increase with an increase 

 of velocity. The time in falling the whole height of twenty-one feet being double the time in falling 

 half the height. These experiments were likewise illustrated (but not so satisfactorily,) by a machine 

 somewhat similar to that of Mr. Roberts. — The pulley was sufficiently distant from the roller to 

 render the angle of tension imperceptible. 



