142 GEOLOGY OF OHIO. 



scrapers are so set as to catch the clay and throw it in a stream under the 

 mullers. The floor of the pan is solid under the wheels, but outside of 

 the area covered by the wheels in revolution, the bottom is made of 

 grates made in sectional plates which can be removed and replaced with 

 ease. 



The clay being crushed fine under the wheels, flies out over the 

 grates by centrifugal force and falls through the grates or is forced 

 through by the scrapers or is carried back under the wheels. When it 

 falls through the floor plates, it is caught in a circular wooden box and 

 is carried around by scrapers attached to the pan floor to a point of dis- 

 charge. 



The capacity of a dry pan varies with the size of its screen plates 

 and with the kind of clay on which it is working. It is highest on 

 brittle flaky shale, and lowest on wet plastic clays. If the clay be too 

 wet or plastic it cannot be treated in a dry pan at all. 



The maximum quantity which is on record for one dry pan in ten 

 hours is two hundred tons of rocky fire clay. The clay was fed from an 

 elevated shute into the pan by gravity by the labor of one man and 

 passed through screen plates of one-eighth and three-sixteenth aper- 

 ture. There is no record in this state to compare with this for efficiency, 

 so far as is now known. 



Under average conditions and with average clay a good dry pan will 

 grind one hundred tons in ten hours through one-eighth screens; one 

 hundred and twenty-five is frequently accomplished in good weather and 

 with dry stock; in wet weather and with snowy or frosty clay, seventy-five 

 tons would be good work. 



There are a number of Dry Pans of a special merit on the market. 

 Each one has some special feature which recommends it. They can be 

 divided into two classesrf=wooden frame and iron frame pans. The 

 wooden frame pans are made for much less money and their makers and 

 many of their users contend that they require far less repair than the 

 iron frame pans; the elasticity of the wood gives the necessary relief 

 from the shocks which are constantly occurring. This may be true, but 

 on the other hand it may be said that the wooden frame pans will require 

 more power to operate them, as it is nearly impossible to keep the bear- 

 ings in line, since the joints of the frame and the bolt holes will work loose 

 in a short time and are bound to become more flexible every month the 

 pan runs. The iron frame pans are neater in appearance and occupy 

 less space, are easier to get around to fill and repair and keep in line; 

 they suffer from shocks it is true, and it may be true that the repair 

 bills on a year's run would be higher; this would have to be proved by 

 records of the two kinds on the same clay, etc., to make the assertion 

 good. 



There are some nine or ten varieties of iron dry pans in use in Ohio. 

 Among them the Frey Sheckler Co. of Bucyrus takes the lead, having in 

 two years sold more pans in this state than any other firm doing business 



