Transactions . Norway pine, secured by wire nails. Broke at 15,000pounds. Xo. 58. Built like Fig. 49. White-pine struts thick,secured by wire nails; 8 oak keys 1 by 2 inches, and12 6-inch steel spikes. Broke at 16,690 pounds. THE EFFICIENCY OF BUILT-UP WOODEN BEAMS. 795 No. 59. Exactly like No. 58. Broke at 13,200 poundsNo. 60. Exactly like No. 58. Broke at 14,800 poundsNo. 61. Four pieces inches deep, built up as in Fig. Fig. 50. Struts of white pine, secured by 2-inchnails. Broke at 8140 pounds. wire Fig. 49.

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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries