In some cases tracing paper is used in making small unimportant drawings. This paper should be of good quality in order that it may stand erasing, since mistakes are liable to occur and these must necessarily be corrected. The best tracing paper is brittle and will not stand much handling. For this reason its use for expensive drawings is not to be recommended.

Stress Sheet. The stress sheets for various structures are usually not made in the drafting room, but are made in the designing room of the company. Much data and many computations are made by the designer which would be of use to the draftsman in detailing. All of this information should be placed upon the stress sheets. The making of a stress sheet should be and usually is done by men of considerable experience. Plates I, II, V, and VI show stress sheets of a truss bridge, roof truss, and a plate girder, respectively, and while these can not be said to be perfect, yet they indicate the engineering practice of our larger bridge corporations and may be taken for examples. (For Plates, see pages 63, 82, 88, and 89.)