1841.1 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



341 



and to temper it. The moulder stands at a table, and the tempered 

 clay is brought to him in lumps of about 7 or 8 lb.: the mould is a 

 box without top or bottom, 9^ inches long, 4| wide, and 2 J deep;t it 

 lies on a table : a little sand is first sprinkled in, and then the lump of 

 clay is forcibly dashed into the mould, the workman at the same time 

 rapidly working it by his fingers, so as'to make it completely close up 

 to the" corners; next he scrapes off with a wetted stick ('s/nfej the 

 superfluous clay, throws sand on the top, and shakes the brick dex- 

 terously out of the mould on to a flat piece of board, (a pallet board) 

 on which it is carried to a place called the hacks formed of the new 

 bricks, into open hollow walls, which (in wet weather) are covered 

 with straw to keep oft' the rain ; here Ihey dry gradually, and harden till 

 they are fit to be burnt. A raw brick weighs between 6 and 7 lb. ; 

 when ready for the clamp it has lost about 1 lb. of water by evapo- 

 ration.* A first-rate moulder has been known to deliver from 10,000 

 to 11,000 bricks in the course of a long summer's day, but the average 

 produce is not raucli more than half this number (1). 



The price of bricks varies from forty to sixty shillings a thousand, 

 of which not more than one shilling and three pence a thousand, at 

 the utmost, can be the cost of moulding, assuming the average work 

 of a moulder to be five thousand in a day ; any improvement, there- 

 fore, calculated to save time in this department of brick-making by 

 the introduction of machinery worked by steam, or by horse power, 

 can only amount to a benefit equal to a fraction of one thirty-second 

 or one forty-eighth of the entire price of the commodity. If we as- 

 sume such machine to produce fifty-two million bricks in a year, this 

 amounts to two millions a week (for the season for brick-making in 

 this country continues no longer than from April to September inclu- 

 sive) or three hundred and thirty thousand in a day, equal to the 

 labour of sixty-six men or eleven horses, without making any allow- 

 ance for friction, or any deduction on account of temporary repairs. 

 The cost of hand-moulding fifty-two million bricks at one shilling and 

 three pence per thousand is 3250/. from which, if we deduct the first 

 cost and repair of machinery, the expense of fuel or of horses, of 

 superintendence, &c. it would probably be found that nothing would 

 remain for profit. 



Bricks are burnt either in kilns or in clamps (2). In the former the 



the knives, by which it is cut and kneaded, and finally is forced through a 

 hole in the bottom of the cylinder. 



* A malm brick of the above dimensions will shrink by burning to the 

 length of 9 or 94 inches. A brick made of top clay without any mixture of 

 chalk, will oileu shrink to 81- inches. 



t From some experiments made in France we learn the following partcu- 

 lars : — A nioukl 8 inches 3 lines long, 4 inches, 3 lines broad, and 2 inches 

 2 lines thick, yieliled bricks which on an average weighed, when first made, 

 5 lb. 14 oz. When dried and ready for the kiln they weighed 4 lb. 8 oz. 

 having 22 oz. of water; 9 oz of this quantity evaporates in the first twenty- 

 four hours, the other 13 oz. require five or six weeks to evaporate. By burn- 

 ing, 4 oz. more of volatile matter is driven off; a well-burnt brick of the 

 above dimensions weighing 4 lb. 4 oz. A fresh-burnt brick when laid in 

 water absorbs about 9 oz- i.e. from one-sevenili to one-eighth of its weight. 



It appears, hdwever, from experiments by M. Gallon, that the weight of 

 bricks varies according to the care with which the clay is worked or tem- 

 pered. Some clay was well worked, and then beaten for half an hour, on the 

 morning of the next day it was again worked and beaten as before, and in 

 the afternoon was again beaten for a quarter of an hour, and was then made 

 into bricks. Another parcel of bricks was made of some of the same clay, 

 treated in the usual manner. Botli parcels were dried in the air for thirteen 

 days, when it was found that those made by the former process weigh d on 

 an average 5 lb. 11 oz. each, while those made by the latter weighed 5 lb. 

 7 oz. Both kinds were burnt together for ten days ; they underwent no 

 relative change in bulk, but the weight of the former was 5 lb. 6 oz. and of 

 the Ipitler 5 lb. 2 oz. — Arts et Metiers, vol. iv. 



(Ij Tlie operation of making the bricks is generally undertaken by one 

 man c.illcd the moulder, who with his wife, children, and one or two men, 

 form a gang. One of the gang, a man, wheels the soil to the nug-mill ; after 

 it is tempered it is removed by a boy or girl from the pug-mill to the banker, 

 (the moulder's work-bench), it is then kneaded bv a woman, who passes it 

 to the moulder next to her, and as fast as the moulder turns the bricks out of 

 the mould, they are removed by a boy on to the off-bearing barrow, wdiich 

 is wheeled to the drying-ground by 1 or 2 men, who set up the bricks in the 

 hacks in a slanting direction, two in width, and about two inches apart, and 

 3 feet high ; these hacks run the whole length of the drying ground and are 

 placed in parallel lines 4 to 5 ft, apart. When the bricks have stood a few 

 days they are reset with a greater space between them, which operation is 

 called sriiiiling, and in about a week after, they are removed to the clamp or 

 kiln. — En. L'. E. &, A. Jour. 



(2) A clamp is formed first by raising the earth a few inches above the 

 natural surface of the ground to an uniform level ; some of the hardest of 

 the ne'.\" made bricks, or, if there be any in the field, some old bricks pre- 

 viously burnt are set on edge over the whole site of the intended clamp, 

 which are to prevent the moisture of the ground penetrating the new made 

 bricks. Flues are then formed by the bricks being laid side by side, with a 

 small space between to the height of 3 feet and about 9 inches w ide ; the top 

 is covered by bricks being set 0(1 on each side, until they form an arch or 

 covering; these Hues run the whole length of the clamp, and generally 



burning is completed in twenty-four hours; in the latter it requires 

 from twenty to thirty days, but is on the whole cheaper, notwithstand- 

 ing that the loss from over-burning, from under-burning and other 

 accidents amounts to one-tenth of the whole number of bricks (3). 



The consumption of London is for the most part supplied from the 

 brick-fields that surround it in all directions, the principal of which, 

 however, are situated north of the Thames, at Stepney, Hackney, 

 Tottenham, Enfield, Islington, Kingsland, Hammersmith, Cowley, Ac- 

 ton, and Brentford. Those made at Grays Thurrock, Purfleet, and 



about ti feet apart j they are filled with furze or dry faggot wood, over which 

 are laid small sea coal, or breeze (cinders), the intermediate sp.aces are filled 

 in with bricks (this operation is termed crowding) laid a short distance apart, 

 and between each coiu'se a layer of breeze is laid and repealed the whole 

 height. The upper courses are laid a little closer than the lower ones, as 

 they receive a greater proportion of heat, the outside of the clamp is gene- 

 rally closed in with place bricks (half burnt or soft bricks), and the top 

 covered with breeze and sometimes earth ; when the clamp is made up the 

 fi.el in the flues is igniteil, which communicates with the breeze laid between 

 each course, and shortly the whole of the clamp is in a state of combustion, 

 and becomes one mass of fire, communicating with the ashes contained in 

 the bricks ; part of the e.xterior is sometimes coated with clay to prevent the 

 cold winds penetrating. As soon as the whole of ihe clamp is properly ig- 

 nited, the flues are closed, when particular attention is retjuired to prevent 

 the fuel burning too fiercely or too slowly. If it bum or draw too quickly 

 on either side, screens are placed on the outside to check the draught. When 

 the whole is properly burnt, which is in about 2.5 or 30 days, the clamp is 

 partially opened and alloii ed to cool ; the bricks are then sorted, those which 

 are properly burned are called stocks — if they arc not suflifiently burned they 

 are of a pale red colour and soft, called place bricks — if the fire has acted too 

 fiercely, several of the bricks will be vitrified into one solid mass, which are 

 called burs. The whole operation of making bricks from the time the earth 

 is turned into the pug-mill to the time the clamp is open, averages about 6 

 weeks. 



The kiln is of an oblong form, brick built, with one opening in the end 

 or side, and generally 13 feet long, 10 ft. 6 in. wide, and 12 feet high; and will 

 contain about 20,000 bricks, the walls, on the top, are about two bricks thick, 

 and at the bottom three Ijricks ; they are built battering (inclining) inwards, 

 the bottom is covered with narrow recesses arched over with openings left in 

 the top, having the appearance of lattice work, in these recesses is deposited 

 the fuel, on the top the bricks are laid with spaces between to allow the fire 

 to pass up ; the upper courses are laid a little closer than the lower ones, and 

 the surface covered over with old brick (ir tie rubbish to keep in the heat 

 and prevent the rain damaging the upper bricks ; when the kiln is full, s me 

 wood is put in and ignited, to dry them thoroughly; «lien this is done, 

 which is known by the smoke becoming transparent, the mouth of the kiln 

 is closed with old bricks and covered with clay, leaving sufl^icient space for 

 faggot ; brushwood, furze, bavins or dry faggot wood to be put in and lighted. 

 The fire being made up it is continued till the ashes assume a whitish ap- 

 pearance, and the flames appear through the top ut the kiln, the fire is then 

 slackened and the kiln cools by degrees. The process iscontinued, alternately 

 heating and slackening till the bricks are thoroughly burned, which is gene- 

 rally in the space of 48 hours. The advantages of kiln burniu" is the greater 

 certainty in the operation and shortness of time in burning, which is done in 

 about two days, whilst the operation of clamp burning occupies frequently 30 

 days. The bricks are generally of a bright and sometimes dark red colour. — 

 Editor C. E. and A. Journal. 



(3.) The following are the prices for the several operations in brick mak- 

 ing :— 



DIGGl.SG PER CUBIC V.VRD. s. d. 



To digging the uncallow, including wheeling not exceeding one run 

 (a run is three 20 feet planks placed in a continuous line, length- 

 ways) . . . . . . .04 



Digging and wheeling brick earth . . . . .04 



Turning and soiling (mixing sand or ashes with the brick earth . 2^ 



M.^KING, PER TUOUS.\Nn. 



Making the bricks, including the tempering of the clay, molding. 



and hacking (stacking) . . . . ' . .40 



.Scintling (removing and restacking the bricks in the hacks) . 2} 



Crowding (placing) the bricks in the clamps or kiln . . 1 4i 



Two yards of clay or brick earlh (which will make one thousand 



bricks) digging and soiling at 6irf. per yard . . .11 



Wear and tear of tools (found by the master) and keep of horse . 2 

 One-filth of a chaldron of ashes for soiling, at 5s. per clial.lron . 1 



One-fifth ditto of breeze for fuel, 7s. (irf. ditto ... 16 



Straw 6rf., sand 6rf. . . . . . . .10 



Kiln or clamp expenses for attending to open it. loading c.iris. &c. 1 

 Duty . . ... . . . .5 10 



Rent . 2 



£1 1 



To the above must be added the expenses for removing the uncallow, risk, 

 losses, interest on capital sunk, &c., and if washed the additional labour and 

 cost of chalk, &c. Stock bricks average at this time abiut 30s. to 32s. per 

 thousand, in the field, and place bricks 24s. The price fi;r the latter is almost 

 prime cost, consequently a greater profit must be allow ed on the sleeks to 

 cover all losses, which in wet seasons are very serious. The duty is obliged 

 to be paid on the quantity in Ihe hack, notw ilhstaudmg any part or the whole 

 may be damaged or destroyed by wet weather or in process of manufacture ; 

 for these risks government allow 10 per cent., reducing the duty to 5s. 3d. 

 per thousand on the quantity made before burning. — Ed. C. E. & A. Jour. 



