material can be reamed, and on which it can be stored so as to remain straight and out of wind. Overhead traveling cranes should be provided for conveying the material to and from the reamers.

Riveting

Rivets should be driven as much as possible by power machines; and machines of different types should be provided, in order to be able to drive the greatest number of rivets practicable. These machines should have ample power, because tight rivets should be secured throughout the work the first time they are driven, the expense of cutting out and redriving rivets being thereby reduced to a minimum. Portable riveting machines probably give the best results, as it is more economical to move a comparatively light riveting machine than it is to shift a heavy piece of bridgework. Machines can be quickly handled and the rivets can be rapidly driven, if the machine is suspended from a wall-crane or a jib-crane. These cranes can be operated from the floor by one of the riveting gang. The bridge members can be transferred by traveling wall-cranes, overhead cranes, or trucks.

Milling and Planing

Certain members of trusses, columns, and sometimes even girders have to have their ends planed; and various machines have been built for this work, a rotary planer being generally the most economical. Milling machines, however, have been used. No matter which type of machine is employed, economy will result by having it furnished with two heads, one of which travels on the ways of the apparatus. This permits the heads to be set at a given distance apart, and both ends of the piece to be planed or milled at the same time, duplicate pieces being finished without re-setting the movable head.

Boring

Double-headed horizontal or vertical boring machines should be provided with one head traveling on the ways of the machine, so that the pin holes can be bored at an exact distance apart. For duplicate parts there will be no need of re-setting the heads.

Special Space

All bridge members do not need to go through the same number of operations in order to be completed; and some provision should, consequently, be made for keeping material that requires only one or two operations (or special operations) out of the Main Shop. To this end a special space should be provided for the fabrication of shoes, cross-frames, laterals, small struts, and other miscellaneous pieces.