Journal of the Association of Engineering Societies (1881)
Association of Engineering Societies (U.S.) · New York, [etc.] Board of Managers · leaf 44
posts and braces were then thoroughly X-braced. The lagging was 8x8 inches spruce, 2 feet on centers and under the lagging, at each intersection with rib, a pair of oak wedges 4 inches wide were placed. The arch sheeting was thus placed on 420 pairs of wedges, there being six ribs under the arch, 5… … Fig. 4. Laying Arch Stones at Bellows Falls. center to center, and on this the "sheeting" was laid. As the in- trados of the arch was rock-faced, an allowance was made for 3-inch projection, the sheeting being kept to line by wedges on top of the plank. This center proved to be most satisfactory,…
Engineering
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