CLAY MANUFACTURES. 715 
mills, 4 presses, 97,000 square feet of drying floors. Its capacity is 
about 11,000 tons of pipe yearly, and about 600,000 No. 2 fire-brick as 
well. , 
The differences in the manufacture of pipe in the Akron and 
Columbus district from the river process begin in the material employed. 
The grinding machinery of the Akron district consist of the machines 
called tracers, and which have so often been alluded to in other connec- 
tions. ‘The tracer is an excellent machine for grinding a true clay of a 
sandy or plastic nature, and though its work in shale is successful, yet 
it seems as if the heavy wet mill of a fire-brick works could not fail to 
be better. It would at any rate grind much more in the same time 
than the tracer, if it did not grind it any better. The fracture of an 
Akron pipe shows frequently small pieces of shale which have escaped 
the wheels, and in burning, these pieces usually shrink away from the 
bond clay so as to make a loose spot in the pipe, and they are conse- 
quently weakening in their effect. As the test of a wet mill has been 
nowhere made, it would surely be a valuable contribution to that dis- 
trict if some operator gave it a fair trial. 
The grinding takes from 45 to 50 minutes, and about 1,200 pounds 
constitute a charge ; the water used is added by the bucketful, and the clay 
is tempered very stiff. In many works they use only $ as many machines 
as necessary, and run part of their plant all night to get the necessary 
clay for the next day’s campaign. The Akron works all use the Barber 
machines, though some of them are of the new style; traces are made 
by the Cuyahoga Falls Co. The ground clay is shoveled into a squeezer 
either of the screw or piston type, and it is concentrated into a long 
compact cylinder about 6 inches or 8 inches in diameter. ‘This is cut 
np in lengths of about 15 pounds weight and is fed to the machine in 
that shape. From this results the worst trouble of the Akron pipe; 
the stiffness of the clay and the large, well-compressed wads in which 
it is fed, act together in keeping the clay from uniting to a homoge- 
neous mass. Even under the powerful pressure of the machine the 
lines of demarkation between the different pieces going to make up a 
pipe, are plainly to be seen on the fracture of a burned pipe. They are 
arranged in circles concentric to the outside of the pipe, and often a 
erack ;!, of an inch separates the layers of the clay. This is all developed 
on burning, but is not visible before to any such degree. The working 
of the clay is admirable. It issues from the press as smooth as if molded 
