Notation.

l = Main span length in feet.

l' = Length of cable of central span in feet.

r = Rise of cable in feet.

B = Angle of inclination of cable at tower.

Ds = Superimposed dead load in pounds per lineal foot of bridge

(exclusive of weight of cable).

L = Live load in pounds per lineal foot of bridge.

s = Working tensile stress in cable in pounds per square inch.

W = Weight of cable in pounds per foot of cable.

Weight of cable in pounds per lineal foot of bridge.

Eye-Bar Cable Bridges, for r/l=1/9

Weight of Eye-bars in Main Span.

Weight of Web Members of Cable.

Notation.

l = Length of main span in feet.

r = Rise of cable in feet.

d = Maximum depth of crescent truss in feet.

p = Panel length of crescent truss in feet.

Ds = Superimposed dead load in pounds per lineal foot of bridge

(exclusive of weight of eye-bars, but including weight of

web members of cable).

L = Live load in pounds per lineal foot of bridge.

s = Working stress in tension in pounds per square inch.

We = Weight of eye-bars in pounds per lineal foot of bridge.

Ww = Weight of web members of crescent truss, in pounds per

lineal foot of bridge.

The span-length selected for the low limit of the computations was 1,200 feet, and that for the high limit thereof was 2,300 feet, thus giving for all diagrams three points through which to pass each curve. Ordinarily, it is not safe to plot a curve through three points only; but in this case there were at hand several similar curves for suspension bridges established previously by the author for another economic investigation, hence no mistake was made in the plotting.

The results of the computations are shown in Figs. 29c, 29d, and 29e. In Fig. 29c are recorded on four separate diagrams the quantities of the various  materials  for  wire-cable  bridges of span-lengths varying from