A FIEST PEIZE TEEATISE 



THE SCIENCE OF EOAD MAKING. 



By Clemens Herschel, 



CIVIL ENGINEER, MEMBER OF THE AMERICAN SOCIETY OP CIVIL ENGINEERS. 



Intkoduction. 



This treatise was written in answer to the printed circular of 

 a Committee of the Board of Agriculture, calling for " treatises 

 upon the science of road-making, and the best methods of su- 

 perintending the construction and repair of public roads in this 

 Commonwealth." 



This circular was issued about the middle of December, and 

 as the time for writing and sending in the called-for essays was 

 limited to January 28, the writer has thought it best, no specific 

 character being prescribed for the treatises, to attempt to write 

 one suitable to be so called from the stand-point of the public, 

 rather than from that of the civil engineer, and, giving results 

 rather than the methods of arriving at them, to be as concise as 

 possible. 



The Science op Road Making. 

 Starting, then, with the first of the two subjects mentioned in 

 the circular, — the science of road making, we can divide this 

 into three periods : (1) laying out a road ; (2) making the 

 road-bed, which includes all earthworks, cutting and filling, cul- 

 verts, drains, bridges, even tunnels, &c. ; and (3) the making 

 of the road surface ; to which, not improperly, might be added, 

 (4) keeping the road in repair. 



Laying out a Road. 

 The considerations which determine the best location of a 

 road, are those arising from the nature of the travel it is pro- 



