tum, or such other material or materials as may be selected by the Engineer.

All holes of any kind, which are bored in any of the timbers, are to be thoroughly saturated with hot asphaltum, and all bolts and faces of washers, which are to be placed in direct contact with the timber, are to be warmed and dipped in a vat of the same material.

The holes for all bolts of three quarters (3/4) of an inch or more in diameter are to be bored one eighth (1/8) inch less in diameter than that of the bolts which are to be used in them. For smaller bolts, the holes are to be bored one-sixteenth (1/16) inch less than the diameter of the bolts.

All caps are to be thoroughly drift-bolted to tops of piles. All bracing timbers are to be bolted to piles, caps, or other timbers wherever they cross them. The ends of all stringers shall be firmly attached to caps by means of drift-bolts, timber cleats, or some other method which, in the opinion of the Engineer, is equally good.

For structures on curves, the superelevation of outer rails is to be provided for by bevelling the ties, not to exceed three (3) inches in five feet, or by dapping inner stringers on caps not to exceed two (2) inches, or, where the required superelevation is too great to be provided for by either of the two methods named or by a combined use of then, by cutting off the tops of the piles on an inclined plane. The last method is not to be resorted to unless it be absolutely necessary, and then extreme care must be taken to cut the piles off so that their tops will lie in a true plane. In no instance is this to be done when framed bents are used, as the inclination can then be given in cutting the tops of the bent posts to receive the caps.

In computing the equivalent loads for Pls. III and IV it was assumed that cars may precede as well as follow the locomotives.

METAL-WORK.

All bolts, nuts, and dowel-pins shall be made of soft steel or wrought iron of the same quality as that specified for adjustable members of bridges  in  Chapter  XVIII  [pages 244  and  following].   Preference