Journal of the Association of Engineering Societies . oston about 1867 or 1868, and was employed atthe Chickering pianoforte factory, where he made the acquaintanceof a fellow-workman, Levi Liscom, who had built wooden bridgesin Xew Hampshire and Vermont. He convinced Liscom, andthrough him several men of financial influence, that his patent solidlever projected without false work from opposite shores was thecoming bridge. A company was formed, and the Oliver street gapgave the opportunity for a conspicuous advertisement. The con-tract price was $1000. It will be noticed that the arch springs
Journal of the Association of Engineering Societies . oston about 1867 or 1868, and was employed atthe Chickering pianoforte factory, where he made the acquaintanceof a fellow-workman, Levi Liscom, who had built wooden bridgesin Xew Hampshire and Vermont. He convinced Liscom, andthrough him several men of financial influence, that his patent solidlever projected without false work from opposite shores was thecoming bridge. A company was formed, and the Oliver street gapgave the opportunity for a conspicuous advertisement. The con-tract price was $1000. It will be noticed that the arch springs from a point far backfrom the fulcrum point of the levers. The reason for this was abrilliant discovery of Cottrells, viz-., that the thrust of the archcould be utilized for balance power to help support the levers. Thearch was an afterthought, and was added to prevent the saggingof the slim center ends of the levers. The theory advanced laterwas that the levers sustained the dead load and the arches the live 36 ASSOCIATION OF ENGINEERING Half Cross-Section A-A I Half Cross-Section B-13.
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectenginee, bookyear1881
