Without the aid of a thoroughly posted bridge-shop engineer, it would be entirely impracticable for anyone who is not truly experienced in structural-steel manufacture to write at all intelligently upon the economics of that branch of bridgework. The author encountered great difficulty in securing the needed aid, partially because the work involved in the preparation of the notes called for many hours of a busy man's time, but mainly because those who are best posted on such characteristically practical matters are not accustomed to express their thoughts on paper.

Failure so to collect one's knowledge is a serious drawback to any man; for he never can determine wherein that knowledge is hazy or lacking until after he has attempted to collect, correlate, and systematize all that he knows upon the subject at issue. Many engineers and others, who in times past have done the author the honor of supplying him with special information, have afterwards assured him that they felt well repaid for the time and effort which they had devoted to the work, through their increase in knowledge obtained in making the investigation. Many a time and oft in his professional career has the author personally proved the correctness of this principle; and he earnestly recommends its serious consideration to the younger members of the engineering profession.

Fortunately in this case, from his old friend, Mr. Thomas Earle, C.E., Vice-President of the Bethlehem Steel Bridge Corporation, the author succeeded in securing the information of which he was in search; and he feels very thankful for the aid rendered, because it is certainly a great concession and a real favor, in the case of an exceedingly busy man, to take the trouble to collect and systematize the special knowledge which he obtained by many years of hard work. The most of what follows in this chapter is essentially the substance of the data so courteously furnished by Mr. Earle.

The economics of design to meet shop conditions has been discussed at length in Chapter XXIII; and Mr. Canady's contribution thereto covers very thoroughly the ground of economics in the drafting-room of a bridge shop; hence there is left for treatment only the economics of doing the work in the shops themselves, together with certain allied economic subjects.

The general economic problem in shopwork is to attain a certain result with the minimum expenditure of effort, time, and money. Each piece of

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