warrant his being retained on the work, can by careful study almost always evolve a better design than can the contractor, even if it be the first experience which the former has had in connection with the portion of the work under consideration. On two or three occasions only, and several years ago, the author was either induced or compelled by the purchaser to defer to the greater experience of the contracting engineer; and in each case he has bad reason to regret the concession; so he has concluded that in future be will receive with thanks any suggestions which the manufacturer may offer, give them due consideration, and then make the design as he himself sees fit.

Considerable opposition to the methods of design advanced in this work and to the specifications given is anticipated, on the plea that the requirements are too exacting and that the class of work called for is unnecessarily refined and consequently expensive. To such opposition the author would reply as follows: First, the designing and building of bridges and similar structures cannot be too well or carefully done; and, second, that within the last three years, upon some fifty or sixty thousand tons of the author's work designed in accordance with the said methods and built in accordance with the said specifications, the prices quoted by the competing manufacturing companies were extraordinarily low, and that no complaint of any account has since been raised by the manufacturers in respect to the expense involved by either the designs or the specifications.

The principles of design given in the succeeding chapter should be adhered to in all structural metal-work and any violation of any one of them is a mistake that will be regretted sooner or later by the parties owning the structure. Many of these principles are violated constantly by shop draftsmen, even when the engineer's drawings show the details correctly. This is due partly to custom in designing certain details in certain ways, and partly to the ignorance of the draftsmen. The author would urge upon young engineers who are working on plans for structural metal-work to adhere to the principles herein given whenever it is practicable for them to do