SIZE FOR MACADAM ROADS. 



227 



bers, and the weight of the heaviest piece when separated for 

 transportation : — 



Since steam-engines, as usually rated by their makers, do not 

 work economically to more than one-half their given horse power, 

 an engine of double the power given in the table had best be 

 bought. 



The whole length of the machines to the backside of the 

 wheels, is from eight to eight and one-half feet ; height to top of 

 wheels, five feet ; width, from four to five feet. 



The machine may be driven by any power less than that given 

 in the table, yielding a product per hour smaller in the same 

 proportion. 



The proper sizes for making macadam, are the fifteen by seven 

 and fifteen by nine for towns and parks. Public institutions and 

 others requiring less quantities to be got out, can use the ten by 

 seven size. 



When broken by hand and for country roads, the stones should 

 be broken on the storage places already mentioned, which are to 

 be established along the side of the road every 200-250 feet. 

 The laborer is not to pound the stones on a heap of such, but to 

 use one large stone as a sort of anvil to break the others on. 

 He is to use a light hammer, except for pieces containing more 

 than four or five cubic feet, and may use a ring with a handle 

 attached to hold the stone he desires to break. 



In order that the road shall get an even surface the macadam 

 must all be of one size, and the proper size for the macadam de- 

 pends on the degree of hardness of the rock. If too small it 



