Transactions . Model of Boston and Maine Key fitted with wedges. pattern in Fig. 46. Beam weighed 63 pounds, broke at 10,900pounds. Check-pieces: A weighed 21 pounds, broke at 3450pounds; D weighed 21 pounds, broke at 3385 pounds. Effi-ciency of beam, per cent. FIG. Cast-Iron Key with Wedge. T-shaped Keys with 49. Exactly the same as No. 41, except that keys werelike Fig. 47. Beam weighed 58 pounds, broke at 9600 pieces: A weighed 21 pounds, broke at 3600 pounds;D weighed 20 pounds, broke at 3550 pounds. Efficiency ofbeam, per cent. THE EFFICIENCY OF BUIL
Transactions . Model of Boston and Maine Key fitted with wedges. pattern in Fig. 46. Beam weighed 63 pounds, broke at 10,900pounds. Check-pieces: A weighed 21 pounds, broke at 3450pounds; D weighed 21 pounds, broke at 3385 pounds. Effi-ciency of beam, per cent. FIG. Cast-Iron Key with Wedge. T-shaped Keys with 49. Exactly the same as No. 41, except that keys werelike Fig. 47. Beam weighed 58 pounds, broke at 9600 pieces: A weighed 21 pounds, broke at 3600 pounds;D weighed 20 pounds, broke at 3550 pounds. Efficiency ofbeam, per cent. THE EFFICIENCY OF BUILT-UP WOODEN BEAMS. 791 No. 50. Exactly the same as No. 49. Beam weighed 58pounds, broke at 9900 pounds. Check-pieces: A weighed 21pounds, broke at 3000 pounds; D weighed 19 pounds, broke at3300 pounds. Efficiency of beam, per cent. Mean effi-ciency of the two beams, per cent. One objection often urged against driving keys is the liabilityof splitting out the daps between the key-slots. The writer hasencountered no such trouble, but on the contrary has been sur-prised to find that, even in Nos. 28, 29A, and 29B, the keyscould be driven up till their edges would be battered up, with-out m any single case splitting out a dap. The ability to with-stand such hard
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
