-I. ABRASION OF THE SURFACES OF SOLIDS. . , . 149 



some interesting results ; but it is only recently that our knowledge of the sub- 

 ject has been materially enlarged. 



The agitation of the canal and rail-road question in the years 1824 and 1825, 

 and the invention or rather revival of a mode of applying steam in lieu of 

 animals to carriages on rail-roads, led to the most extravagant conclusions : 

 and although the doctrines of Coulomb and Vince, relative to the equality of 

 resistances under different velocities, have been still further confirmed by the 

 expei-iments of many able persons in this country, such as Chapman, Grimshaw, 

 Wood, Tredgold, Palmer, Roberts, and others, and much valuable informa- 

 tion elicited ; — our progress in the science has been but slow and unsatisfactory. 

 Sensible of these defects, and being unable to profit by the valuable treatises 

 subsequently published, it occurred to me that a series of experiments founded 

 on the omissions of former writers would be extremely desirable. 



The present series of experiments relates to the friction of attrition. This 

 branch of the science comprehends the resistance occasioned by solid bodies, — 

 such as ice, cloth, paper, leather, wood, stones, metals, &c. gliding over each 

 other simply, or by the intervention of semi-fluids or unguents, such as oil, 

 tallow, &c. 



The object has likewise been to determine the powers to resist abrasion 

 under the circumstances of surface, pressure, and velocity. Examples have 

 been sought, 



1st. From ice, by the resistance of its surface to sledges, skates, &c. 



2nd. From cloth, by its remarkable properties of resistance in opposition to 

 the law observed by solids. 



3rd. From leather, by its great utility in the pistons of pumps, &c. 



4th. From wood, in its application to pile driving, carpentry, launching of 

 ships, &c. 



6th. From stones, as relating to the equilibrium of arches and buildings. And 



6th. Fi-om metals, from their universal application to machinery ; but more 

 particularly to wheel carriages and rail and other roads, on which a great 

 many experiments have been made. 



Experiments on a great scale, however, frequently involve so many contra- 

 dictions, from the difiiculty of obtaining the necessaiy elements, that I have 

 deemed it preferable to offer the present series, as comprehending in a greater 

 degree most of the cases in question, and affording a more systematic view of 

 the nature of the investigation. 



