630 NEW YORK STATE MUSEUM 



addition of sand. Along the Hudson river and on Long Island 

 tempering sand is a mncli needed article, but fortunately it is near 

 at hand. With molding sand it is different, for wherever soft mud 

 machines are used it is necessary. Very often it can be obtained 

 from some neighboring hill, but sometimes it has to be brought 

 long distances. 



Having determined by boring or otherwise, the extent and 

 thickness of the clay at the locality where the brick yard is to be 

 established, the next step is to strip a portion of the surface to a 

 sufficient depth to expose the clay. 



The amount of stripping to be done varies. On Long Island 

 it is sometimes as much as 20 or 30 feet. Along the Hudson 

 valley it varies from a foot or two of loam, or 3 or 4 feet of sand 

 up to 15 or 20 feet. In both these regions the sand can be used 

 for tempering, though the quantity stripped is far in excess of the 

 demand. At some points in the Hudson valley the surface is cov- 

 ered with scrubby trees troublesome to remove. In the northern 

 and western portions of the state, there is at most places only a foot 

 or two of soil covering the clay. 



When a yard is first started, the stripping, whatever its charac- 

 ter, can be used for filling. 



I^atural drainage is always an extremely desirable thing, for 

 having to keep the clay pit clear of water only adds to the cost of 

 production. jSTeighboring streams and springs are often a constant 

 source of annoyance, specially if the clay deposit is situated in at 

 valley. They are chiefly troublesome when the sand bed, which 

 often underlies the clay, is struck and allows the water to run in 

 and flood the workings. 



The presence of a sufficient quantity of clay or shale does not 

 insure quality, and before erecting a clay-working plant, it i& 

 necessary to examine into the quality of the clay and its possible 

 applications. 



The laboratory methods of investigation have reached a high 

 degree of development at the present day, and by such means much 



