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NEW YORK STATE MUSEUM 



diameter and so geared that it travels from the center to the cir- 

 cumference of the pit and then toward the center again. In 

 this manner the clay is thoroughly broken up a ad mixed with the 

 sand and coal dust, if this latter be added. The pitfull is 



Ring pit for tempering clay 



tempered in about six hours, and a pit holds sufficient for about 

 30,000 brick. The tempering is usually done in the afternoon so 

 as to have it ready for the next morning. When the tempering 

 is finished, a board is attached by ropes to the wheel and dragged 

 round the pit a few times to smooth the surface of the clay ; a 

 thin crust forms on the surface and prevents the moisture in the 

 underlying material from evaporating. 



With ring pits there is a similar arrangement as with soak pits, 

 the only difference being that the temperer previously mentioned 

 is generally employed in the morning to wheel the clay from the 

 ring pit to the molding machine. 



As a rule there are two ring pits to a machine, so that while 

 the clay is being shoveled from one pit to the machine, the other 

 pit is tempering clay for the next day, or two pits and two 

 machines are used, but each pit in this case holds enough material 

 for the daily use of two machines. 



Pug mill. — This machine, like the ring pit just described, is 

 used for thoroughly mixing the clay, or clay and sand as the case 

 may be, before introducing it into the machine. It consists 



