A treatise on architecture and building construction . Fig. 62. are cut out of 2-inch plank, to a radius about 1 inch lessthan that of the intrados of the arch. At c are indicatedpieces of plank, nailed at the crown of the center to spliceand stiffen it. Small bearing strips b, about 1 in. X 2 in. insection, are nailed to the curved pieces a. At d are thelongitudinal braces; at c are the plates under the center andon top of the posts; at/ are the wedges; and at g, theposts, which, if quite long, should be braced at the middleby struts. 8 MASONRY 63 113. For arches of considerable span, centers
A treatise on architecture and building construction . Fig. 62. are cut out of 2-inch plank, to a radius about 1 inch lessthan that of the intrados of the arch. At c are indicatedpieces of plank, nailed at the crown of the center to spliceand stiffen it. Small bearing strips b, about 1 in. X 2 in. insection, are nailed to the curved pieces a. At d are thelongitudinal braces; at c are the plates under the center andon top of the posts; at/ are the wedges; and at g, theposts, which, if quite long, should be braced at the middleby struts. 8 MASONRY 63 113. For arches of considerable span, centers morestrongly built are necessary. Fig. 63 shows a good form ofconstruction. At a and b are represented the bearers, break-. FlG. 63. ing joint as shown; c indicates the bearing strips; r, theupright; d, the inclined braces; /, the tie piece; ?, the bear-ing plates, with wedges g between; and //, the side andcenter posts. POINTING sto:n^ework. 113. The effects of the weather on the exposed edgesof the joints in masonry usually cause the mortar to crumbleand fall out. For this reason, it is customary to refill thejoints, to a depth of from \ inch to 1 inch, with speciallyprepared mortar. This operation is called pointing. It isgenerally done when the walls are completed, but, if theseason is too far advanced, it should be deferred until no circumstances should it be done in freezing weather, 64 MASONRY. 8 nor in extremely hot weather, as then the mortar will dry toorapidly. Portland cement mortar, made of equal parts of sand andcement, and such coloring matter as may be desired, mixedwith just enough water to give a mealy consistency, makesthe most durable mortar for pointing. 114. Before applyi
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