This section is from the book "Modern Buildings, Their Planning, Construction And Equipment Vol1", by G. A. T. Middleton. Also available from Amazon: Modern Buildings.
Fig. 103 also shows examples of obtuse squints formed by walls of various thicknesses meeting at various angles from 100 to 170 degrees, the shape of the quoins having been found by the above method. This method of finding the shape of the quoin brick holds good for all angles from just less than 180 to 112 degrees, in which last case the size of a brick limits the application of the method (see Fig. 104).
In squints of less than 112 degrees a different and even simple method is employed. The quoin brick is formed by splaying a whole brick from one corner to the required angle, as in Fig. 104. Measure AB, which in this case is 8 1/4 inches, subtract 2 1/4 inches, which leaves 6 inches, and place a closer next to the shorter face of the quoin brick, so that AC may be equal to 6 inches. The walls are then built from the corners as in right-angle junctions, and overlap one another in such a manner as to produce simple cutting with no small pieces of brick and no continuous vertical joints. There is no doubt that the reader will be able to devise other methods of fitting in the interiors of the walls at the angle, but those shown in Figs. 103 and 104 are of a very simple nature and comply with the principles of sound bonding, while they bear a great semblance to one another in their minor detail.
Of course, in the above examples the quoins should be carefully cut to the plan obtained by the method shown in Fig. 103 where neat work is required, while in rougher work a bricklayer will obtain a very near approximation to the correct shape by guess work.
In squint piers of small dimensions it is impossible to devise any universal system for bonding the bricks, but a particular method must be devised for each particular case. Fig. 105 shows examples of squint piers of dimensions likely to occur in practice.
A universal method of bonding squint piers of any dimensions is shown in Fig. 106, and the slight modifications, which are in some cases advisable, will be demonstrated afterwards. It is supposed in Fig. 106 that the outline plan has been taken off a plan. The method of procedure is as follows: Lay the stopped ends first of all, and then starting from the stopped ends lay the external facing bricks until there is room for no more. A space is left at the corner, and to fill this a brick is taken, and along one of its faces the distance EF is measured; the brick is splayed from the point E to the required angle, and the brick cut to fit the space left. The rest of the wall is then filled up according to the rules already demonstrated, thus completing one course. The next course is the same as the first, viewed through the back of the paper upon which it is printed.
The question which naturally arises at this point is, Why does this method give a satisfactory lap? The reason is a simple one. The differences between the distances EF and EG, EB and EH, etc., are always equal to 2]- inches, because the difference between AB and DC is 2 1/4 inches. It is quite possible to have a pier of such dimensions as to necessitate making the quoin brick very small, when the brick should be shaped as in Fig. 107 in order to make the angle more solid. It is better, however, to make the quoin brick as large as possible, and this can be done by laying the quoin along the other face of the pier, as shown in Fig. 108.