337 



BRICKS. 



BRICKS. 



338 



the water attacking the foundations should be frequently changed; 

 but if the water should be stagnant, it may happen, when the bricks 

 contain a large proportion of soluble silica, that the free lime of the 

 mortar may form with it a stable combination which will greatly 

 increase the strength of the mass. This peculiar action is known 

 amongst working men by the phrase of the brick-work being " water 

 bound ;" and it may be observed to occur when rather soft kiln-burnt 

 bricks have been used in permanently damp ground, in connection with 

 rich lime mortar. In tidal works, however, or in positions where the 

 water is frequently renewed, none but the hardest bricks and the most 

 energetic cements should be used ; and this precaution must always be 

 adopted in those parts of a building exposed to alternations of dryness 

 or of humidity. 



Brick-work, in the neighbourhood of London, is reckoned at so much 

 per rod, or the unit of bricklaying accounts is the rod of 272 feet 

 superficial, of work 14 inches thick ; that ia to say, of 11J cubic yards, 

 or 306 cubic feet. Assuming that the bricks are laid with a close 

 joint, to a gauge of four courses to 11J inches in height, there will be 

 required 4500 stocks and 71 cubic feet of mortar in a rod. The weight 

 of a cubic foot of brick-work in cement is about 105 Ibs., and that of a 

 cubic foot of brick- work in mortar is about 98 Ibs. In most tables of 

 specific gravities, that of brick-work is quoted as being 1'87 ; but this 

 is rather in excess of the real facts of the case. 



Bridcmoking by Machinery. We must now attend to those re- 

 markable modifications of the processes which have been due to the 

 introduction of machinery. Rapidity of production is not the only 

 reason for the adoption of machines. It has been found in some of 

 the brickwork of railway arches and tunnels that the outer or most 

 exposed bricks have a tendency to decay, from the alternations of 

 temperature and moisture to which they are subjected ; and it is as a 

 means of lessening that tendency, by increasing the solidity and close- 

 ness in the adhesion of the clay of which the bricks are formed, that 

 machine-made bricks have often been recommended. 



About 1836 Messrs. Heaton of Birmingham, who had before intro- 

 duced a mode of tempering the brick-clay by rolling, devised a machine 

 for moulding the bricks as well as preparing the clay. The machine 

 consisted of a horizontal wheel, round the margin of which were 

 arranged a number of brass moulds, the proper size and shape for 

 bricks. The bottom of each mould was loose and moveable vertically 

 by a small apparatus beneath, connected with a little wheel. The 

 wheels of all the moulds worked on a circular railway, having such an 

 inclination as to leave the bottom of the mould in its proper position 

 when at one part of the circular course, but lifting it up to the top of 

 the mould when the latter had travelled round half a circle. When 

 any of the moulds came to a particular part of the circuit, a loose board 

 was put into it by an attendant, a stream of water was forced into it 

 from a forcing pump, and the tempered clay, coming from the rollers 

 through which it had been pressed, and passing through a hopper, was 

 forced by a plunger into the mould ; then, the mould advancing one 

 step in its circuit, a knife-edge sliced off all the superfluous clay, and 

 rendered the upper surface smooth. The mould continued to travel on 

 in its circular path, and its bottom, with the newly-made brick, became 

 lifted up gradually ; until, by the time the half -circuit had been made, 

 the brick was lifted wholly out of the mould : a man then took off the 

 brick, and prepared it for burning in the usual manner. It was a 

 necessary feature in this arrangement, that all the moulds were in 

 different states or stages at any one instant of time ; half of them con- 

 tained bricks, half contained none ; one was just receiving its supply 

 of clay, while another, exactly opposite, was yielding a finished brick 

 to the hands of the workman ; and of the rest, some were having the 

 loose bottoms slowly raised to elevate the bricks resting on them, 

 while others were gradually resuming the form fitted for the reception 

 of clay. 



In 1838 M. Terrason introduced a mode of making bricks differing 

 considerably from the above. There are three parts of the apparatus, 

 destined respectively to kneading the clay, moulding the bricks, and 

 transporting them when made to a yard or depository. In the first 

 process, two horses, attached to the two arms of a lever, work some 

 revolving cutters in a cylinder, by which the clay is thoroughly kneaded. 

 The second machine, destined to mould the bricks, is placed near the 

 former one, and receives the fillet of clay as it exudes from the cylinder. 

 The mould for the bricks is simply an oblong channel or hollow frame, 

 having neither cover nor bottom, but one roller working above it and 

 another below it The clay enters this trough, the width and height 

 of which give the proper width and thickness of a brick ; while the 

 two rollers, pressing the clay above and below as it enters, give the 

 proper flatness of form to the upper and lower surfaces, compress the 

 clay Into a solid consistency, and expel the superfluous portions. The 

 clay, in fact, passes through a kind of rolling-press. When the oblong 

 trough has been removed, by reciprocating action given to it by 

 machinery, from this press, the board on which the clay rests becomes 

 released from the side-boards of the trough ; then on passing under a 

 particular part of the apparatus, the oblong fillet of clay is cut into 

 ten or twelve bricks, by the descent of as many wires stretched across 

 above them. In the third machine, by means of a long row of cylinders 

 working on an inclined plane, the board of bricks is carried to any 

 convenient distance, where they are deposited previous to burning. 



In the same year another machine wag invented by Mr. Jones, in 



AIIT9 AMD 8CI. DIV. VOL. II. 



which the clay, being mixed with a less quantity of water than usual, 

 was kneaded in a pug-mill to a stiffer consistence than ordinary, 

 thereby rendering a shorter period for drying sufficient. The rate at 

 which the bricks were made by this machine was stated to be from 

 one to two thousand per hour. 



From about the year 1840 the suggested or patented improvements 

 in brick-making have been very numerous ; but they do not call for 

 lengthened description. In Mr. M'Nab's method there is a sliding- 

 frame beneath the bottom of the mill in which the clay is ground ; 

 and this frame contains two brick-moulds, so arranged that while one 

 of them is under an opening in the bottom of the mill, receiving clay 

 from thence, the other is outside the mill delivering a moulded brick ; 

 the two moulds being alternately placed in .communication with the 

 mill. The bottom of each mould consists of a moveable bed, which, 

 when the mould has arrived outside the mill by the movement of the 

 frame, forces the brick up out of the mould, to be removed by an 

 attendant. Another method introduced about the same time, had a 

 peculiar adjustment whereby a screw forces the clay out of the mould, 

 and wires descend to cut it into bricks. A method patented by Messrs. 

 Cook and Cunningham is on a different principle. Here a sliding 

 mould-frame, containing two moulds, is applied to the side of the mill 

 in which the clay is prepared. The clay is forced, by the rotation of 

 arms within the mill, through an opening into a box ; and a piston 

 working in this box presses the clay into one of the moulds in the 

 sliding frame. When one of the moulds has been thus filled, the frame 

 moves forward, which brings the other mould under the box, while 

 the first mould is carried over an empty moveable mould placed on a 

 table ; a piston presses the brick into the empty mould, and the mould 

 thus set free returns to receive a fresh supply from the box. The 

 mode is thus so far a continuous one that while one mould is empty- 

 ing its contents into the moveable one, the other is receiving a fresh 

 supply at the box ; while a boy receives the moulded bricks from the 

 moveable mould as fast as they are deposited in it. Mr. White's 

 patent, of the same year, related principally to an improvement in the 

 mode of supplying the clay from the mill. 



Mr. Gibbs has proposed a method in which both the materials of the 

 bricks and the mode of manufacture are taken into account. He pro- 

 poses to use Merstham sand or pulverised Merstham sandstone, com- 

 bined with London clay or pipe-clay ; in proportions varying according 

 as bricks, tiles, or pottery are the object of manufacture. The mode 

 of making bricks under the patent embraces two or three modi- 

 fications, of which one consists in rolling the clay out into a sheet of 

 uniform thickness, then cutting it by machine- worked knives or wires 

 into brick-shaped pieces, and compressing these by a separate machine. 

 An American method introduced more recently by Messrs. Beach and 

 Lukeus, seems to be founded mainly on the plan of Messrs. Heaton, 

 but to contain a provision for transporting the bricks to any convenient 

 spot by means of an endless belt. 



Mr. Prosser has introduced a method of making bricks, tiles, and 

 small articles of earthenware, from earth or clay almost in a state of 

 dryness, by intense pressure in metallic moulds. 



The weight of bricks, made by any method, is an important matter in 

 relation to the purpose for which they are to be applied. In a con- 

 versation at the Institute of Civil Engineers, after the reading of a 

 paper relating to bricks, several engineers objected to the use of bricks 

 made wholly by machinery, on the ground that their extreme com- 

 pactness made them heavier and more costly than common bricks, and 

 delayed their drying. Mr. Hunt has, for this reason, brought into use 

 a contrivance where hand-power and slight pressure are substituted for 

 machine-power and heavy pressure. The decision as to the general 

 introduction or not of machine-made bricks, will probably depend, as 

 in most other cases, on the relative expense in comparison with the 

 hand method ; hitherto they have been rather too costly. At Roorkee, 

 in the north-west of India, where extensive engineering works have been 

 carried on, requiring a hundred million of bricks, great economy has 

 been found to result from the introduction of a brick-making machine 

 from England. 



It may be well to notice one peculiar manufactured article, which 

 receives the name of a brick from its shape, and not from its use or 

 purpose. A manufacture peculiar to, and constituting a staple trade 

 of Bridgewater, is the fabrication of that kind of white brick known as 

 Bath Brick, so krgely used in knife-cleaning ; this branch of industry 

 gives employment to many of the inhabitants. These bricks are 

 formed of the sediment or sand of the river Parret, cast into moulds 

 and dried. 



Bricks, like many other articles of manufacture, underwent many 

 varieties in the rate of duty imposed. The tax was first laid in 1784, 

 at 2s. 6d. per thousand. In 1794 it became 4s., and in 1803, 5s. In 

 1835 the duty was increased to 5s. Wd., for common bricks of ordinary 

 size. In 1803, bricks of larger size were taxed to the extent of 10. 

 perthousand. Polished bricks were 12s. I0d., and large polished 24s. 2rf. 

 The words of the Act referring to glazed bricks were " smoothed and 

 polished ;" and so strict were the revenue officers, that bricks struck 

 with a bat or on a table to straighten them if warped, were considered 

 to be " smoothed and polished," and were charged with the extra duty. 

 At length, in 1850, this vexatious duty was removed ; and a beneficial 

 result was almost immediately perceived, by allowing scope for the 

 exercise of inventive talent. The maker, under the old law, had no 



