concerning the comparative merits of several layouts, and can ascertain where and how any particular layout can be improved. A consultation with several members of one's office force upon the architectural features of the various designs will often result in an improved effect; for nothing else will bring out both the favorable and unfavorable characteristics of a plan like discussion.

In the outlining of each span a great deal can be accomplished towards beautifying a structure, and there is no better way to study the general effect of any proposed outline than the one just indicated, viz., laying out various trusses to scale tacking the paper to a wall, and criticising them. It will surprise any one who tries this method to see how quickly he can detect the slightest variation from correctness in outline, and what a difference in effect even a small change in a truss depth will produce. It was in this way that the trusses of the Omaha draw-span were proportioned and it is doubtful if any improvement could be effected in their outlines when all factors involved in the question are duly considered. In this problem there were but three points to determine, viz., the depths of truss at the two hips and the depth at the tower, for the number of panels was settled by economic considerations, and the straightness and section of the top chords were necessitated by certain questions of efficiency. The depth at the outer hips was first determined by the requirements for clearance, rigidity, and appearance, then the depths at the intermediate hips and tower were settled by trial and discussion from the artistic point of view, due attention being paid to the engineering questions involved by the various inclinations of top chords and inclined inner posts.

In determining the outlines of a span these few elementary principles are to be borne in mind:

1st. There is nothing so ugly in a bridge as parallel chords unless it be a skew. However, for spans between one hundred and twenty-five feet and two hundred feet it is often best to use them, although in certain cases where the loads are great it is practicable to adopt polygonal top chords for spans considerably shorter than the superior limit just mentioned.