CLAY WORKING INDUSTRIES. 237 



The preparation of the clays where the shales are used, is by 

 dry pan and screens. When the drift clay is used, such thorough methods 

 are not required. Brick are made at Independence, by the Boyd Press- 

 by the Whittacre at Oakland; and by the Hydraulic at Findlay. 



The brick at both Independence and Zanesville are dried in steam 

 heated dryers, using cars as a means of transportation. At Findlay the 

 brick are set directly in the kiln and are dried by the heat of one of the 

 cooling kilns which is blown in to the green kiln by a fan. This method 

 was alluded to more fully in the remarks on drying of paving brick. The 

 burning is accomplished by down draft kilns of rectangular form. Each 

 factory uses a different kiln, one the Eudaly, one the Griswold and one 

 the Graves. 



The two factories located one at Union Furnace, and one at North 

 Baltimore, are entitled to special credit as being the pioneers in the line 

 of new architectural work alluded to before. The Union Furnace plant 

 is located in the edge of the Coal Measures, and has in the hills surround- 

 ing it a series of strata, comprising three or four veins of fire-clay, 

 besi es several shales and surface clays of value. The colors produced 

 are a line of buff brick, comprising ten. or twelve shades; a line of so 

 called terra-cotta shades, which are a mixture of buff and dull red; and 

 a line of grays, which are very light buff with pure, black. Other lines 

 of colors have been experimented on and produced on a small scale. 



The North Baltimore Plant produces a similar line of buff brick, and 

 also a fine red color. They have also gone into the manufacture of 

 enameled brick. 



In these two works, the efforts of the manufacturers have been to 

 meet the architects half way in the production by accurate and scientific 

 means, of whatever colors, shades and shapes may be needed for artistic 

 work in construction. 



The mixtures are controlled by weights and thorough care is taken, to 

 keep the stock always uniform, so that the production of the shades of 

 any one color will fall inside the regular classified grades. In these 

 works the process of manufacture is distinctly less important than the 

 accurate control and grading of the product. 



It is found necessary for each line of colors to establish not less than 

 ten or twelve shades of that color due to the variations of the burning, 

 and position in the kiln. The accurate grading of the brick into shades 

 is a matter of great delicacy and expense, and yet on this stage of the 

 work the artistic value of the product depends. 



The process of manufacture is by use of the dry-pan and screen and 

 Boyd brick press at Union furnace, and by Steadman disintegrator and 

 Simpson brick press at North Baltimore. The burning is accomplished 

 by down draft kilns at both plants. At Union Furnace, there are two 

 large continuous kilns of the Guthrie patent. The principle of these 

 kilns is undoubtedly correct as it involves the use of the waste heat of 



