205 



Tho 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 saturated with water was found, which was 

 entirely unsuited for a stable foundation. 



The excavation was carried below the line of permanent satura- 

 tion, and foundation piles driven from eight to sixteen feet before 

 reaching a firm substratum. The piles were sawed off about fifteen 

 inches above the bottom of the excavation and the spaces between, 

 and for one foot outside of them, was filled with cement concrete 

 and well rammed. Longitudinal timbers, twelve inches square, were 

 placed on the tops of the piles, and were secured to them by iron 

 bolts seven-eighths of an inch square, and seventeen inches long. 

 Upon these, at right angles to them, were placed other timbers of 

 the same size, which were notched down so as to interlock with those 

 first laid. These timbers were all completely imbedded in cement 

 concrete. Upon these timbers, planks six inches thick were laid, so 

 as to leave alternate spaces equal in width to the plank. These spaces 

 were filled with concrete. 



The timber work is all placed at such depth as to ensure its dura- 

 bility ; being below the line of permanent saturation. 



Upon this sub-structure the large stones of the foundation masonry 

 were laid. The balance of the foundation to within one foot of the 

 grade of the walk is constructed with large blocks of gneiss rock 

 laid in cement. 



The face stones above the walk to the springing line of the arch 

 are of Hudson River " mountain graywacke." Work was suspended 

 at this point for the season. 



The archway in the East Wood is designed to carry a carriage 

 and bridle-road over a walk. 



The facings are of Ohio and Belleville sandstone alternating, and 

 the interior arch is of common hard brick. This is to be lined with 

 panel work in wood. 



In excavating for the foundation of this archway, a coarse com- 

 pact gravel was found, and the excavation was carried only three feet 



