CIvAY WORKING INDUSTRIES. 147 



The two methods in use are by Wet Pans and by Pug Mills. ' 



The wet pan process is used in almost all of the sewer pipe factories, 

 and in many brick works, while the use of pug mills is nearly limited to 

 brick works and similar works. 



The wet pan is a counterpart of the dry pan except that its bottom 

 is solid instead of perforated and its mullers are generally narrower in 

 tread and lighter in weight. 



The usual wet pan muller has a face five or six inches across and 

 weighs from 1,500 to 4,000 pounds. The scrapers are not so long nor 

 set so deep, nor with so flat an angle in the wet mill as in the dry. 



The framing, be it iron or wood, is just like the dry mill and the 

 gearing, etc., are also just the same or a little lighter. 



The mode of operation consists in running a charge of clay from 

 600 to 1,200 pounds into the pan from a large box or shute with proper 

 valve for controlling it. While the clay is running in, the water is also 

 turned on, and is being mixed with the clay by the combined action of 

 the scrapers and mullers. When clay and water are added in sufficient 

 amount, they are shut off and the grinding progresses. As the clay gets 

 more uniformly wet and plastic the wheels cut through it cleaner and 

 grind and crush the particles as they pass under. The grinding action is 

 not to be overlooked in this process. The mixture secured is intimate 

 in proportion to the length of the grinding; two and one half minutes 

 will temper a charge for brick thoroughly; for sewer pipe four or five 

 minutes ought to be consumed. As the tempering progresses the opera- 

 tor adds water as is needed. When the charge is ready to withdraw it is 

 taken out by a shovel. The blade of the shovel is made of wood about 

 18x24 inches, and the handle is a heavy bar of wood, 3x4, pivoted on a 

 ring bolt near the blade end. 



The shovel is lowered into the pan where it is instantly filled by the 

 clay sliding upon it. It is then lifted out and dumped into the boot of 

 the elevator or conveyor which is to take it away. 



This operation is always done by the operator who does the temper- 

 ing. One man can run two wet pans comfortably, filling, tempering and 

 emptying in rotation so that one pan is grinding a charge while the other 

 is being emptied and filled. 



There are two devices in use for emptying the wet pans automatically. 

 The first and simplest device has been perfected simultaneously by two 

 men, working independently. It consists of the 'shovel arrangement just 

 described, actuated by machinery, so that it comes down, pauses a moment, 

 raises, dumps and comes back again with no help but starting and stop- 

 ping. This device simply saves labor on the part of the temperer, but he 

 must be there just the same and paying attention to his work just the 

 same. It accomplishes the work so much easier and quicker however, 

 that it is alleged that the capacity of a wet pan is increased from twenty 

 to thirty per cent, by its adoption. 



