TERRA-COTTA, BRICK, ETC.
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Brick-Making Machinery.
Space and time both prevent the consideration of this subject in detail, permitting only brief notices of some of the machines.
The two principal types are the piston machines, and those for continuous delivery through dies of the size and form of the section of the brick. Of the former there was an example in the United States section, and of the latter in the Austrian.
Gregg’s Excelsior Brick Press.— The celebrated brick press, invented by William L. Gregg, of Chicago, and which was honored with a prize medal at Paris in 1867, was exhibited in model. This invention, which has been improved since 1867, is competent to produce fifty-six bricks per minute, or twenty-six thousand to thirty thousand bricks in a day of ten hours. And it is claimed by the inventor that bricks of the lower grades can be made by this machine for less than one- half, and face or front bricks for about one-third the cost of making by hand.
The machine has two sets of moulds, seven in each set, fixed upon a movable table which passes back and forth under a feeder through which clay is forced into the moulds. When filled, the contents receive, in the movement, two distinct downward pressures from a wheel above. The bottoms of the moulds are movable, and are attached to a piston which slides up on an inclined plane as the carriage or table moves °ut from under the wheel. This forces the bottom of each mould upward, carrying with it the brick, and when all are out of the moulds they are swept off to one side, the empty moulds return under the hopper and the process is repeated. The clay is taken directly from the bank, and is prepared for the moulds by two grinding rollers. From the discharge of these rollers it is elevated to the hopper of the machine.
The rapidity of the production of the moulded clay bricks is uot the only great advantage of this system. The clay need u°t be so wet as is necessary for hand-moulding, and thus a great saving of time in drying results. Hand-made bricks as they come from the moulds must lose twenty-five per cent, of Water by artificial drying or spontaneous evaporation before it