Many expedients have been used to connect the metal-work of the suspended spans of cantilever bridges, and considerable trouble has often been experienced in doing the work, owing to variations in both length and elevation. The author is of the opinion that but little difficulty will be experienced if the following precautions be taken:

First. See that the entire triangulation is so accurately done that there will be no possibility of an error exceeding one quarter of an inch in the distance between centres of pins over main piers. A perusal of Chapter XXIII. will show that this is perfectly feasible.

Second. See that extra precautions are taken by the inspectors during the manufacture of the metal-work to insure that all lengths of main members shall be absolutely correct.

Third. See that the tapes used in shop and field are of exactly the same length.

Fourth. Use toggles like those described in this chapter for effecting the adjustment.

Fifth. Arrange to have the meeting ends of the chords a trifle high, so that lowering and not raising will be necessary.

Sixth. Arrange matters so that when the ends of the metalwork come together they will be a trifle apart rather than tending to lap, for it is much easier to heat the chords slightly by suspending beneath them sheets of metal containing slow fires than it would be to cool them by packing ice around them in cloths.

Referring now to the before-mentioned special investigations made by Mr. Hedrick, the questions set him for solution at the outset thereof were the following:

First. The ratio of the economic length of suspended span to that of the total opening.

Second. The most economic length of anchor-arms when the total length between centres of anchorages is given, and when the main piers can be placed wherever desired.

Third. The relations between the weights of metal in the suspended span, cantilever-arms, anchor-arms, anchorages, main pedestals. and anchor spans.

Fourth. The best proportionate length for anchor spans, and the comparative weights of metal in those of different lengths.