McMaster, John Bach, 1852-1932, Making of America Project · New York, D. Van Nostrand · leaf 101
ayfive or six are placed at a time. Thus,starting at the springing line, we adjustsix laggings on each side of the frame,and carry the arch up equally on bothsides. When it has reached the upperbolster, we add six more, and the masonry continued as before, and proceed inthis way until very near the… … 97 these rabbets cross or key ing-in*laggings B, consisting of stout planks18 or 20 inches in width, are laid one ata time beginning at one end of the centring. The bricklayer whose duty it isto key-in the arch stands with his headand shoulders between the brickworkA, A, and starting at the end of…
Bridges · Tunneling
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