the loading of a much smaller width of deck will produce maximum stresses in any one cable.

The next economic consideration is the design of the stiffening trusses. It must be remembered that the weight of these is a direct function of the live load and entirely independent of the dead load, which passes immediately from the floor to the suspenders and cables without causing either moment or shear on the trusses. It is, consequently, expedient to keep the live load down to the lowest legitimate limit consistent with the probable loads from future traffic.

Custom has decreed that the truss depth should be about one-fortieth of the span length, but a greater depth would reduce the weight of metal in the chords without increasing materially that in the web. It is claimed that a greater depth than this established limit would not be aesthetic, but this can be determined only by careful study for each case as it arises.

The choice of panel length may be determined from the standpoint of aesthetics or by an economic adjustment between floor-system and trusses. This question also will require careful study.

The system of cancellation adopted for the trusses will have quite a little to do with their weights of metal, but the consideration of appearance should govern in this matter. If a single-intersection truss be adopted, it will have the advantage of avoidance of ambiguity in stress distribution, but it will not provide as pleasing an appearance as will the double system of cancellation. In the latter the vertical posts, as far as the question of statics is concerned, are superfluous; but without them the secondary stresses would run high, the connection of the floor-beams to trusses would be awkward, and the proper attachment of the trusses to the cables would be difficult. It is better, therefore, to adhere to the use of the vertical posts when the double-intersection type of truss is selected. These posts, though, may be made of minimum section consistent with their appearance and with the function which some of them perform in distributing the load to the cables.

An economic point of importance is that of having the ends of stiffening trusses free or anchored. The latter condition is more economic of metal in chords, but there is little or no difference for the web; however, it necessitates extra metal and expense for the anchoring, but the resultant effect invariably is a reduction in the total weight of metal, and hence the expedient should generally be adopted.

The selection of the versed sine for the cables is a matter of economic importance. Increasing it reduces the sectional area of cables and backstays, but augments slightly their lengths; and it adds to the height and weight of the tower columns and their bracing.

On the other hand, it effects a slight saving in mass and cost of anchorages due to the reduction of overturning moment that is caused by the diminution of stress in the backstays. Experience has shown that a depth of catenary  equal  to  one-ninth  of  the  span  will  usually give the most satis-