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Upon this road bed is placed a layer of the coarse sand found 

 on the park, twelve inches in thickness, which is properly formed 

 and rolled. Upon this is laid with care a course of Telford blocks, 

 seven inches in depth ; next is a layer of four inches of McAdam 

 stone, and this is followed by three inches of Roa Hook gravel. 



The rubble road differs from the Telford mainly in the substitu- 

 tion of sound rubble stone in the place of the Telford blocks. 



As water and stone are the great destroyers of roads, one of the 

 first requisites in the construction of a good road is to provide 

 ample and effective drainage, both of the surface and the sub- 

 structure. 



To secure the proper sub-drainage, tiles are laid on the line of 

 each gutter, at a depth of three feet and six inches below the surface, 

 and are connected directly with the silt basins. 



To ensure the speedy removal of surface water, a crown of from 

 six to nine inches, depending upon its width, is given to the road- 

 way. 



The gutters were constructed two feet in width, three inches in 

 depth, and made of the very best quality of paving brick, laid on 

 edge and well bedded in cement mortar. 



At suitable intervals along the gutters, silt basins were placed, 

 having grated inlets, through which the surface water enters, and 

 thence passes into the general drainage system. 



The Telford blocks were obtained from the boulders which abound 

 on the park, and furnish a very superior material. 



The blocks are somewhat regular in form, being from four to 

 seven inches in width, from five to nine inches in length, and about 

 seven inches in depth. They are generally broken slightly, wedge- 

 shaped ; and are laid with the broadest base downward. 



Wedge-shaped cavities are thus formed in the upper surfaces ; 

 these are filled with spalls which are well rammed, forming a 

 close and comparatively smooth surface to receive the McAdam 

 stone. 



Suitable McAdam stone is found in great abundance on the 

 park. The stones were broken by a Blake's patent stone breaker, 

 which readily breaks to any required size, from forty to sixty cubic 

 yards per day. 



The broken stone, in falling from the machine, passes over 

 screens which remove the dust and finely-broken stone, leaving 

 the balance quite clean and of uniform size. The size generally 

 used is from one and a half to two and a half inches in the largest 

 diameter. 



