BRICK 



529 



The bricks having been thus formed and released from their moulds, they are to be 

 removed from the bed of the machine by pushing forward, on the front side, fresh 

 boards or pallets, which of course will drive the bricks out upon the other side, whence 

 they are to be removed by hand. 



There is to be a small hole in the centre of each pallet, and also in the bed, for the 

 purpose of allowing any superfluous earth to be pressed through the moulding boxes 

 when the pistons descend. And in order to cut off the projecting piece of clay which 

 would be thus formed on the bottom of the brick, a knife-edge is in some way con- 

 nected to the bed of the machine, and as the brick slides over it, the knife separates 

 the protuberant lump ; but the particular construction of this part of the apparatus is 

 considered to be of little importance, and the manner of effecting the object is not 

 clearly stated in the specification. 



Fig. 259 represents Mr. Hunt's machine. The principal parts consist of two cylin- 

 ders, each covered by an endless web, and so placed as to form the front and back of 

 a hopper, the two sides being iron plates, placed so that when the hopper is filled 

 with tempered clay from the pug-mill, the lower part of the hopper, and consequently 

 the mass of clay within it, has exactly the dimensions of a brick. Beneath the hopper 

 an endless chain travels simultaneously with the movement of the cylinders. The 

 pallet-boards are laid at given intervals upon the chain, and being thus placed under 

 the hopper, while the clay is brought down with a slight pressure, a frame with a 

 wire stretched across it is projected through the mass of clay, cutting off exactly the 

 thickness of the brick, which is removed at the same moment by the forward move- 

 ment of the endless chain. This operation is repeated each time that a pallet-board 

 comes under the hopper. 



259 



There are numerous machines in use for the manufacture of bricks. For the 

 manufacture of perforated bricks, Mr. Beart's machine is the most generally em- 

 ployed. Mr. Chamberlain thus describes it : ' The most universally used die-machine 

 which has been extensively worked up to the present time is Mr. Beart's patent for 

 perforated bricks. This gentleman, who is practically acquainted with these matters, 

 in order to remedy the difficulties I have mentioned in expressing a mass of clay 

 through a large aperture or die, hung a series of small tongues or cores, so as to form 

 hollow or perforated bricks. By this means the clay was forced in its passage 

 through the die into the corners, having the greater amount of friction now in the 

 centre. Still, the bricks came out rough at the edge with many clays, or with what 

 is termed a jagged edge. The water-die was afterwards applied to this machine, and 

 the perforated bricks, now so commonly used in London, are the result. In Mr. 

 Beart's machine, which is a pug-mill, the clay is taken after passing through the 

 rolling-mill, and being fed in at the top, is worked down by the knives. At the 

 bottom are two horizontal clay-boxes, in which a plunger works backwards and for- 

 wards. As soon as it has reached the extremity of its stroke, or forced the clay of 

 one box through the die, the other box receiving during this time its charge of clay 

 from the pug-mill, the plunger returns and empties this box of clay through a die on 

 the opposite side of the machine. The result is, that while a stream of clay is being 

 forced out on one side of the machine the clay on the opposite side is stationary, and 

 can, therefore, be divided into a series of five or six bricks with the greatest correct- 

 ness by hand. Some of these machines have both boxes on one side and the plungers 

 worked by cranks. This machine cannot make bricks unless the clay has previously 

 passed through rollers, if coarse ; for anything at all rough, as stone or other hard 

 substance, would hang in the tongues of the die. But the clay being afterwards 

 pugged in the machine is so thoroughly tempered and mixed, the bricks when 

 made cannot bo otherwise than good, provided they are sufficiently fired. As to tho 

 utility of hollow or perforated bricks, that is a matter more for the consideration of tha 



VOL. I. MM 



