Hasluck, Paul N. (Paul Nooncree), 1854-1931, ed · Philadelphia, D. McKay · leaf 164
11! 2iO t35 XUJO1-Q h- 1 N PI / (I JII iJ? hBH ^H If i llfiiBl … TIMBER ROOFS. 145 beam truss of 50-ft. span is as follows :—A derrick is erected and held in nearly anupright position by guy ropes. A block andtackle are secured to the top of the derrick,at the lower end of which a single block is required by men working the crab; Toprevent the truss swaying and…
Carpentry · Joinery
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