114 GEOLOGY OF OHIO. 



cost of an average kiln is from $1,500 to $2,000, with a capacity of 7,000 

 gallons per burn. 



2. The heat is irregularly distributed, being greatest at the ends and 

 least in the center. 



3. The fuel consumed is higher in proportion to the output. From 

 unofficial figures furnished by several manufacturers on each side, it ap- 

 pears that the round kiln will burn ware with from ten to twenty per 

 cent, less coal per 1,000 gallons. 



It is thus seen that there are many things to be said pro and con 

 about this kiln. In one works, one of these kilns was burned fifty- one 

 times, in fifty-two consecutive weeks and no money was spent in repair 

 in that time. A record of this kind can only be accomplished by the best 

 of care and management. 



The Round Downdraft Kiln, regarded by many as the stoneware kiln 

 of the future, is built in all sizes from sixteen to twenty-five feet in diam- 

 eter. The latter is the largest size used in the stoneware business, and it 

 is not in favor with those who have to operate it. The prevalent sizes 

 are twenty and twenty-two feet which hold respectively 7,000 and 9,000 

 gallons. Of course these figures as to capacity depend on the kind of 

 ware being set. They are intended to represent the average. 



The kiln is usually about seven feet high to the spring of the arch 

 from the floor, and the fire places arranged at equal spaces around the 

 circumference, number from seven to ten. 



The fires are smaller than those used in the Akron kiln. Some are 

 arranged with the Akron fire hole, more often they used the incline grate 

 bars and open front. The "bags" or "pockets" inside run from 4 to 6 

 feet up the wall. The floor is checkered and is usually built from eigh- 

 teen to thirty inches higher than the level of the surface of the yard and 

 higher than the bottom of the fire holes. This is the most important 

 point in the construction of the kiln, and stoneware men, more than any 

 other class of clay workers, have realized the value of the raised floor, in 

 getting the heat down to the bottom and making an even burn. It saves 

 at both ends; it takes less draft to operate the kiln and less coal to burn 

 it. The points for and against this kiln are conversely the points of the 

 square kiln ; the}' will be merely recapitulated. In favor : 



1. Cheapness of first cost and repairs. A twenty-foot kiln of the best 

 material and construction can be put up for $1,000 to $1,200. 



2. Heat is distributed evenly at all points around a center; there is 

 no hot end or cold spot. 



3. Economy in fuel. 

 Against : 



1. Takes up more room. 



2. Is easier to smother, but if the burner knows his business, there 

 is less need of smothering: as it is easier to drive the heat to the center of 



