Chap. XXIV.

MASONRY.

1471

the vertical plane forming this joint. To draw the curve corre-plan, set off on the parallels which indicate the projections tho

projection ofto gh on the

° d 8 A "h 7 8 • 6 a V

Fig. 2667. vis saint gilles, on a square plan.

o'to'jonti,* \ and the J . oint S>1 on the e ' eTation from 3 to 3, from 4 to 4, and from

wmfxpress thlt nart Wlth a flexible rule throu S h the Points A3, 4 g, a curve which

vation. The sairm m.-u/a 6 - lro , ram l 1 1 ant of the joint, indicated by hg on the plan and ele-observe that those whi h° d 1S ad ° pted to find the curvature of the other joints : we must

t0 the middle of the faces ° f ‘ he "-'I s a » d of

o half ellinQPc^TOUr, l e primitive centre: the centres on the direction of the stepsare half-ellipses, whose lesser semi-axis, indicating the height of the centre, is alwavs the