the preparation of the design or in the work of the drawing room. Even where considerable freedom is allowed in the way of modifications to suit the standard methods, details, and equipment of the particular shop doing the work, the fact that such modifications must be arranged for with the Engineer, as well as their actual accomplishment, involves a certain delay and slowing down in getting the work under way in the drawing room. The engineers thereof must necessarily make complete investigation of the geometry, fits, etc., including the requisite number of large-scale layouts, independent of the completeness of the design. The manufacturer is always (and properly so) held responsible for the correct fit of the steelwork. The Engineer's preference for certain types of details, or details that are required by the conditions of erection, should, of course, be indicated as a part of the design.

"The spacing and arrangement of rivets should not be fixed; for the limitations of the specifications as to the maximum and minimum spacing ought to be sufficient. The designer should always keep in mind that modern bridge shops are equipped with multiple punches and various spacing devices, and that contract prices are based upon the largest possible use of such machines. Erection difficulties and impossibilities are often incorporated in such complete designs, which objectionable features must be 'ironed out' by the engineer responsible for the shop drawings before the detailing can go ahead. He has as his particular field the following duties:

"1. To make details for carrying out the specifications and properly

developing the strength of the parts connected.

"2. To detail so that the shop can fabricate most economically.

"3. To detail so that the erection methods and the equipment de-

termined upon for the particular bridge shall be not only pos-

sible but economical as well. The sequence in the placing of

the different members must be taken account of throughout the

entire detailing.

"The engineer at the plant, versed in the preparation of shop drawings, is both by experience and environment the best qualified man to meet these three necessities. In fact, the last two are never possible of final solution until after the contract has been signed and the work is being developed in the shop drawing room.

"It is, of course, conceded that, for unusual or monumental structures, the makeup of the details is so interwoven with the general design that the development of the two must proceed together. Even in such cases it is nearly always necessary for the best results that modifications be made as the work progresses in the drawing room.

"The correctness of the foregoing statements has been proved by the actual experience of our Shop Engineers covering their work reaching over a period of the past twenty years. We are now so well fortified with examples