CLAYS OF NEW YORK 769 



Elbows and Y's are made by molding tbe clays in plaster molds; 

 or in the case of Y's and T's, straight pieces of pipe are sometimes 

 trimmed to fit together in the desired shape and the parts cemented 

 by slip. Such complicated pieces need to be dried more slowly. 



Sewer pipe are made from 2 to 2 2 feet in length; the diameter 

 ranges from 3 to 30 inches. 



New York sewer pipe industry 



Angola. John Lyth & Sons. The works are situated along the 

 Lake Shore railroad some few hundred feet southwest of the sta- 

 tion. The material used is the Portage shale, of a gray color and 

 containing streaks of bituminous matter. It is mined about 200 

 feet east of the factory. A small blast serves to loosen a large 

 quantity of it. A part of the bank is roofed over to protect the 

 workmen in winter. Cars drawn by horses convey the shale to 

 the dry pans, where it is ground to a fine powder and then farther 

 ground with the addition of water in a wet pan. The tempered 

 material is carried in a bucket ladder to the upper floor of the 

 building, where it is fed into the sewer pipe press. , 



The composition of the shale used at Angola is 



Silica = ..., = .....>, 66,15 



Alumina 15 . 29 



Oxid of iron 6.16 



Lime '. 3.50 



Magnesia 1.57 



Alkalis . . . ■ 5.71 



97.38 



At the present time hollow brick and terra cotta lumber form 

 the chief product of the factory. 



Rochester. Otis & Gorsline use a mixture of ISTew Jersey fire 

 clay and Quaternary clay obtained from Chili, near Rochester. 

 The method of manufacture followed by them is very similar to 

 that at Angola. Rectangular kilns are however used for burning, 

 which takes about one week. 



