Page:Willich, A. F. M. - The Domestic Encyclopædia (Vol. 1, 1802).djvu/382

350&#93; 35<*] BR I bricks. stones, or any other build- ing materials to be substituted for those articles, may be so form- ed, as to be applied with peculiar advantage in the erection of wall-, and in the construction of arches. (Dated April 14, 1795.) His im- provement consists in giving bricks such a shape or form as that, when in work, t:.ey shall mutually lock into, or cramp each other. The principle of his invention, he says, will be readily understood, by sun- posing the two oppo-ite -ides of a common brick to have a groove or rabbet down the middle, a little more than half the width of the side of the brick in which it is made : there Mill then be left a shoulder on each side of the groove, each of which shoulders will be nearly equal to one quarter of the width of the side of the brick, or to one half of the groove or rabbet. — Buildings constructed with bricks of this principle, will require* no bond-timber, one universal bond running through, and connecting the whole building together : the walls of which can neither crack nor bulge out, without breaking through the bricks themselves. "When bricks of this simple form are used for the construction of arches, the sides of the grooves or rabbets, and the shoulders, should be the radii of the circle, of which the intended arc'.i is to be the segment. In forming an arch, the bricks must be coursed across the centre on which the arch is turned, and a grooved side of the bricks must face the workman. They may be either laid in mortar, or dry, and the interstices after- wards rilled, and wedged up, by pouring in lime-putty, plaster of Paris, grouting, or any other con- venient material, at the discretion B Ri of the workman, or builder. ?t is obvious, that ;:rches upon this principle, having no lateral pres- sure, can neither expand at the foot, nor spring at the crown, con- sequently i hey will want no abut- ments, requiring only perpendicu- lar walls to be let into, or to rest upon ; and they will want no in- cumbent weight upon the crown, to prevent their springing up;, a circumstance, at' great importance in many situations, in the construc- tion of bridges. Another advan- tage attending this mode of arch- ing is, that die centres may be struck immediately; so that the same centre (which in no case need be many feet wide, whatever may be the breadth of the arch) mavbe regularly shifted, as the work pro- ceeds. But the greatest and most striking advantage attending this invention is, the absolute security it affords (and at a verv reasonable rate) against the possibility of rirej for, from the peculiar properties of this arch, requiring no abutments, it may be laid upon, or let into, common walls, no stronger than what are required for timbers, of which it will preclude the neces- sity, and save the expenee. — For a more particular account, we refer the reader to the third volume of the " Repertory of Arts and Ma- nufactures" p. 84, and following, o which he will also rind annexed two plates illustrating the subject. 2. Mr: Francis Fakqaharsox, of Birmingham, obtained a patent (dated Febr. 20, tfgfy for machi- nery formakingbrieks andtiles ; and, 3. Mr. James Douglas., also, for a machine for making bricks, of the same date; but as we are not in possession of the specifications bf the. two last-mentioned patents, we shall content ourselves with men- tioning;