712 GEOLOGY OF OHIO. 
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The press consists of a large steam cylinder, upon a high iron frame ; 
the piston runs into a second cylinder of less diameter situated beneath 
it; this is called the mud-drum or mud-cylinder, and into it the elay to be 
pressed is introduced, and from its lower end it is forced out as pipe by 
the pressure from the upper or steam cylinder. The piston at the upper 
limit of the stroke leaves a passage into the inside of the mud-drum 
near the top, which is closed as the piston moves down further. Into 
this opening is shoveled the tempered clay. It is tempered so dry that 
it may be shoveled with perfect ease, and it has no tendency to stick 
together by contact alone, though it does so readily by pressure. The 
cylinder being filled with clay, the piston is given steam and moves down 
slowly, consolidating the clay and expressing the inclosed air through 
small holes in the piston head and the cylinder bottom. When, through 
these holes, the clay begins to issue, the pressman knows that the clay 
has filled the shape of the cavity perfectly ; and as the bottom isa 
movable one, it is loosened and dropped upon a balanced platform close 
beneath it. This platform under the weight of the cylinder head, which 
is so shaped as to form the pipe, is just counter-balanced, and by any 
pressure can be moved up or down, carrying the socket shaper on its top. 
The bottom being pushed out of the way, continued pressure from above 
causes the pipe to issue. When enough has come out, it is cut off by a 
rotary knife from the inside, and the separated length of pipe is carried 
away either on a cart or in the hands. It is next sponged and pared, 
to smooth it. The pipe is shaped by being forced out between the wall 
of the mud-drum and a conical core which is suspended from higher 
up in the drum. This cone parts the clay evenly on all sides, and 
causes it to leave the press in an even, regular shape and thickness. 
The dimensions of the presses used are various ; the Pittsburgh press at 
Walker’s has a steam cylinder 44 inches in diameter, and 23 inches 
of mud-drum. The ordinary diameter is from 35 to 36 inches, and 
about 18-inch mud-drum. ‘Those presses which are used for small pipe 
only are 24-inch cylinders and 12-inch mud-drum. The gang necessary 
to run a press are: Ist, one man to fill the mud-cylinder ; 2nd, one 
engineer; 3rd, one man to cut the pipe and help handle the pipe; 4th, 
one man to manipulate the socket shaper; 5th, from one to three men 
to carry off the pipe. At one of the Elliottsville works, a press is in 
use having two mud-drums parallel, which are filled and pressed alter- 
nately, so that the press may work constantly instead of filling, pressing 
