240 MASSACHUSETTS AGRICULTURE. 



13,775 feet tons @ 2,000 lbs.=2.09-2.61 mile tons per cubic yard 

 of macadam. 



Pavements and Trackways. 



No essay on roads would be complete without some mention 

 of these two species of road-surface, though the use of the 

 former is confined principally to streets, and that of the latter is 

 out of date. 



Pavements are either of stone, wood, iron, various concretes, 

 asphalt, and may be of still other substances. 



Stone Pave7nents. — The modern sizes of paving stones may 

 be seen from the following cases. The Boston size is 4^"X3|^" 

 X7" deep; New York Belgian, 6-8"x5-6"x6-7" deep; new 

 Broadway pavement, also called Guidet pavement, 3|-4|"XlO- 

 14"x7^-8-|-" deep. This last is laid with the long sides of the 

 stones across the street ; and, as far as the author's judgment 

 goes, is the best size for stone pavement there is. The Boston 

 size is too small, and allows of no bond between the separate 

 paving stones. Further, the weakest part of each stone being 

 its edge, it follows that the more edges there are in a given sur- 

 face of pavement, the speedier will it wear out, each stone be- 

 coming rounded and slippery. It is only the excellent work- 

 manship and great care displayed in setting these stones in 

 Boston that prevents these facts from being at once apparent to 

 all. When it is added that in setting pavements, the natural 

 soil, except it be sand or fine gravel, is in all cases to be exca- 

 vated 12-19 inches, and then filled up 5-12 inches, according 

 to the solidity of the subsoil, with clean, coarse sand or fine, 

 clean gravel, and the paving stone set in this and well rammed 

 down with hand rammers, about as much is said on this topic 

 as can be said without going into long details. 



From four and one-half to six cubic feet of sand are required 

 for every square yard of paving. In setting two different pave- 

 ments, the same written rules may be exactly followed in either 

 case, yet one be much better than the other, so much depends 

 here upon good, careful, conscientious workmanship. 



Wooden Pave?nents. — There are so many kinds of these, that 

 it would be out of place to enumerate and describe them all 

 here. Their advantages are, less wear on tires and horses, less 

 noise and smooth traction ; a disadvantage, is their slipperiness 



