often convenient to do a considerable amount of drawing and writing in pencil on the sheet. Another reason for using the rough side is that any erasure shows less thereon than it would on the smooth side, and it is often necessary to do considerable erasing on tracings.

As before stated, the first drawings to be made are the general profile and plan with cross-sections, to establish all the main dimensions of the structure. These drawings can be prepared before the computations are finished. Next come the stress-diagrams, which should contain the cambered lengths of all members, the dead load, live load, impact and wind-load stresses, and the greatest combinations of same, the sections required and those used for each main member, and the following general data:

First. Length of span from centre to centre of end-pins.

Second. Number of panels.

Third. Perpendicular distance between central planes of trusses.

Fourth. Depths of trusses.

Fifth. Dead load for floor system per lineal foot of span.

Sixth. Dead load for trusses per lineal foot of span.

Seventh. Live load for stringers per lineal foot of span.

Eighth. Live load for floor-beams per lineal foot of span.

Ninth. Live load for trusses per lineal foot of span.

Tenth. Wind load on upper lateral system per lineal foot of span.

Eleventh. Wind load on lower lateral system per lineal foot of span.

Twelfth. Clearance required above base of rail or floor.

Thirteenth. Kinds of materials to be employed in all parts of structure.

Fourteenth. Diameters of rivets to be used.

The stress-diagram proper may be simply a line-drawing, each main member being represented by a single right line, or all the main members may be drawn to scale by means of their periphery-lines. The latter method is generally adopted because of the improved appearance of the sheet which it affords. The scale  for  any  stress-diagram  should  be  large  enough to