CLAY WORKING INDUSTRIES. 143 



here. Their pan unites more good points than any other in general use 

 though several pans have been built but not yet extensively marketed, 

 which would equal it in every way. 



Among the other pans deserving special commendation are the Bon- 

 not pan of Canton, the Carlin of Pittsburgh, the Penfield of Willoughby. 

 The Turner Vaugh & Taylor, of Cuyahoga Falls, and the Hayden of 

 Columbus must also be mentioned. 



The average price of a nine foot dry pan of the best design is $ 1,000 

 to $1,100. 



The wooden frame pans are used more generally in sewer pipe shops 

 than in brick factories, probably because the sewer pipe shops are largely 

 old and the brick factories have been built since the use of the iron dry 

 pan has become popular. 



The makers of wooden frame pans supply a much more nearly uni- 

 form machine than those who make pans with the iron frame. The price 

 including the timbers framed ready for erection is about $700 and $600 

 will often buy the bare castings. The frames are of 12x12 oak usually 

 and are made as strong as they well can be. 



The wooden frame pan is probably wasteful of power, but requires 

 less mechanical skill and care, than the iron frame. In wooden frame 

 pans, that made by Jas. Means of Steubenville divides the honors 

 with the Stephenson Pan of Wellsville, among the clay working establish- 

 ments of the state. 



The fineness to which it is advisable to grind in the dry pan before 

 allowing the fine material to escape for more accurate sizing in the screens, 

 is a question on which some, experimenting could profitably be done. 

 The usual practice is to use plates with about -$% aperture when new ; as 

 the plate wears the apertures rapidly become larger, so that as the differ- 

 ent sections are put on at different times, one can find spaces any where 

 from -^2 to \. The action of the pan is much more vigorous and effective 

 when the fine material is kept screened out, for if fine dirt and coarse 

 together are allowed to run under the wheels for a few revolutions they 

 pack into a dense cake which prevents any effective work at all. On the 

 other hand it would seem foolish to allow material to escape from the pan 

 to go to the screen which is not yet prepared to pass through it. The 

 proper course lies between the extremes; the pan plates ought to be so 

 regulated that not less than 66 per cent, of the product will go through 

 the screens and probably 75 per cent, is in most cases the better propor- 

 tion. If the screen plates are too coarse no useful result is accomplished, 

 for the tailings from the machine must all be returned to be reground, 

 and energy is being expended in elevating and screening material which 

 cannot go through the screen. 



The screening of the ground clay from the dry pan is the next step 

 in the process. 



