BRICK MAKING. 22t 



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bricks are formed with a s^roove clown the middle, a little more 

 than half the width of the side of the brick, leavmj^ two shoulders, 

 each of which will be nearly equal to one half of the groove. 

 When these bricks are laid in courses, the shoulders of the first 

 course tit into Ihe i^rooves of the second, and (he shoulders of the 

 second fall into the f;rooves of the first, thus forming an indented 

 line of nearly e'|ual divisions. The grooves, however, ought to be 

 somewhat wider than the two adjoining shoulders, to allow for 

 mortar, &c. The construction of these bricks is perfectly simple ; 

 but the principle will be preserved, in whatever form of indenture 

 they will be made to lock into, or cramp each other. Brick walls, 

 consiructed upon this principle, require no bond timber ; one uni- 

 versal bond connecting the whole building, which can neither craok 

 nor l)ulge out without bieaking through the biicks themselves. 

 This invention is also particularly useful in the constructioii of 

 arches ; and when employed for this purpose, the shoulders of the 

 bricks and the sides of the grooves should be radii of the circle, of 

 wliich the intended arch is a segment. It is, however, recom- 

 mended, that if the arch be particidarly flat, or aj)plied in situa- 

 tions which do not admit of end walls, to have the shoulders dove- 

 tailed, to prevent the arch from cracking across, or giving waj 

 edgewise. In forming an arch, the bricks must be coursed across 

 the centre, and a grooved side of the bricks must face the woi-k- 

 men. The bricks may be either laid in mortar, or dry, and the 

 interstices afterwards filled up by pouring in lime-putty, Paris plas- 

 ter, or any other convenient material. The obvious advantages of 

 arches constructed upon this principle, are, that the same centre, 

 which, whatever be the breadth of the arch, may be in no case 

 many feet wide, may be regularly shifted as the work proceeds ; 

 and as they have no lateral pressure, they require no abutments to 

 prevent their expanding at the foot, nor any weight upon the crown 

 to prevent their springing up. They may be laid upon a common 

 perpendicular wall, and if used in the construction of common 

 buildings, they will not only prccliuie the necessity, and save the 

 expense of timber, but will also allurd an absolute security against 

 the possibility of fire. 



A new invention in the formation of bricks, by M. Legressier, 

 has lately been announced in the Archives (Us Decouvcrfes et ties 

 Inventions Nouvelles^ Pendant Pannee 1809. The principle, how- 

 ever, is merely that of Mr. Cartwright's, followed out to a greater 

 extent than has perhaps ever been done in this country. M. Le- 

 gressier proposes, that the bricks should be formed in seven dif- 

 ferent moulds, according as they are to be placed in the middle or 

 on the exterior of the walls ; in the bottom or on the top ; in the 

 arches or in the corners ; and by the proper disposition of (hese 

 bricks in the building, every pressure, either longitudinally or 

 laterally, is resisted, in proportion to the strength of the indentures 

 by which they are locked together. 



Besides the place bricks, and grey and red stocks, which are 

 ttised in common buildings, there are inarle facing bricks, cutting 



