J. A. L. WADDELL C.E. (Rens. Poly. Inst.); B.A.Sc., Ma.E., D.Sc. (McGill Univ.); D.E. (Doctor of Eng., Imp. Univ. of Japan) Knight Commander of the Japanese Order of the Rising Sun; Membre de la Société de Bienfaisance de la Grande of the American Society of Civil Engineers; of the American Institute of Consulting Engineers; of the Franklin Institute; of the Institution of Civil Engineers, London; of La Société des Ingénieurs Civils, Paris; of the Canadian Society of Civil Engineers; of the Western Society of Engineers; of the Rensselaer Society of Engineers; of the Engineers' Club of Kansas City; of the Society for the Promotion of Engineering Education; of the American Association for the Advancement of Science; of the American Society for Testing Materials; of the International Society for Testing Materials; of the American Rail- way Engineering Association; of La Société de Géographie de France; of the Phi Beta Kappa Society; of the Tau Beta Pi Society; of the Sigma Xi Society; of the National Conservation Association; of the Economic League; and Honorary Member of the Kogaku Kyokai (Japanese En- gineering Society), and of the Société "Concordia," Paris IN TWO VOLUMES FIRST EDITION FIRST THOUSAND NEW YORK JOHN WILEY & SONS, INC. LONDON CHAPMAN & HALL, LIMITED 1916 Copyright, 1916, by J. A. L. WADDELL PUBLISHERS PRINTING COMPANY EXPEDIENTS IN DESIGN AND CONSTRUCTION IN bridge engineering practice the term "expedient" may be defined as a method or detail of construction evolved to meet some new or unusual condition. What may properly be termed an expedient in one year may have become established practice in the next; for usually engineers very properly adopt everything new which is of real value in designing and construction. But, because of either the inherent modesty of bridge engineers or of their lack of time to make records, or possibly on account of the well known general disinclination of busy men to write for publication, many valuable expedients are used once or twice and then forgotten. To record some of these is one of the objects of this chapter, but its true raison d'être is to impress upon young engineers and students of engineering the fact that it is almost always possible to evolve some method of overcoming any obstacle that may arise in either the designing or construction of bridges, all that is requisite being an intense and earnest application of mental energy to the problem. Knowing that in his own practice the author had evolved at various times expedients worth recording, and not wishing to illustrate this chapter by his own work alone, in 1907 he wrote to a number of his engineering friends and acquaintances who specialized in bridgework and asked them to cooperate with him by sending him descriptions of some of their expedients. A few of them complied with his request, but a number very modestly stated that they could think of no special work of theirs worth recording. The author regrets that his attempt was not more successful, and he takes this occasion to thank sincerely the gentlemen who did comply. He will now reproduce the salient portions of their letters before recording certain expedients of his own. Edwin Thacher, Esq., C. E., of the Concrete-Steel Engineering Company, and well known both as a consulting bridge engineer and as the inventor of one of the best slide rules ever put upon the market, wrote as follows: "I can think of but one expedient resorted to in my experience which is worth recording. It is as follows: A few years ago I was consulting engineer for a bridge across the Merrimac River at Newburyport, Mass. The Boston Bridge Works were contractors for the bridge, and Shailer & McCormick were subcontractors for the substructure, which was of steel cylinder piers filled with concrete. The bridge consisted of four fixed spans of 206 feet each, and a pivot span of the same length. The pivot pier was built of seven 6-foot cylinders, one of them being at the centre; and each of the other piers consisted of two 8-foot cylinders. The bridge had a 34-foot roadway and one |