2d. While it is generally economical of material to use very long panels, no such extreme length should be adopted as would involve an awkward appearance due to flatness of diagonals.

3d. The curvature of the top chord should be made as great as is consistent with a proper consideration of web stiffness and counterbracing.

4th. When it is practicable in Petit trusses to curve the top chord to such an extent as to make too small the inclination of the end-posts to the horizontal, it is permissible to let the latter extend over one panel only and to make all the main diagonals extend over two panels. The effect is ungraceful, however, when the main diagonals occupy one panel each near the ends of the span, and two panels each elsewhere.

5th. When appearance alone is in question trusses very deep at mid-span are desirable; but an excessive truss depth is conducive to a reversion of bottom-chord stress—a condition which has either to be avoided or provided for by stiffening the bottom chords. In extremely heavy bridges, especially where the dead load is unusually great, it is possible that an undue consideration for economy of metal might cause a designer to adopt a truss depth which would be actually too great for appearance, but this is not likely to occur very often because of other limiting conditions.

6th. There are certain limiting relations between width of bridge, depth of truss, and length of span which for the sake of good effect ought not to be exceeded. Usually the rules established on account of purely engineering questions will prevent these limits from being transgressed, thus proving a maxim which the author has often maintained, viz., that in any design any violation of engineering principles is also a violation of good taste from an artistic point of view.

7th. A very graceful effect can be obtained by placing the lower horizontal struts of the overhead bracing in a cylindrical surface similar to that which contains the panel points of the top chords, but, of course, with different curvature.

In respect to the decoration of each span of a bridge, it may be stated that a little ornamentation is generally much better