53 



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 roadway. 



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 arc thus formed in the upper surfaces; these 

 are filled with spalls which are well rammed, forming a close and com- 

 paratively 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. 



The gravel used for the final surfacing of the road is obtained from 

 Roa Hook on the Hudson River, and is of a very superior quality, 

 being of uniform hardness and free from dirt. 



The sand and gravel for the sub-structure of the roads, gutters, &c, 

 is obtained in great quantities on the Park. 



ARCHWAYS. 



But two archways have been commenced this season. One near the 

 main entrance, and the other in the east wood. 



In making the excavation for the foundation of the first mentioned 

 structure, a tenacious clay satured with water was found, which was 

 entirely unsuited for a stable foundation. 



