tion that the load on one pair of wheels is distributed equally over three ties, the effect, of impact being considered. No tie shall be less than seven (7) or preferably eight (8) inches wide, nor less than six (6) inches deep, nor less than ten (10) feet long, except in the case of elevated railroads, where the length may be reduced to eight (8) feet for a spacing of five (5) feet between central planes of longitudinal girders.

Ties shall be dapped to a full and even bearing not less than one-half (1/2) inch onto the stringers; and each alternate tie shall be secured thereto at each end by a three-quarter (3/4) inch hook bolt, having at the hook end a square shank at least two (2) inches long to prevent the bolt from turning.

All timber bolts shall be of soft steel, with cold-pressed threads.

Outer guard-timbers shall be 6" X 8" laid on flat, dapped one (1) inch onto the ties, and placed so that their inner faces shall be just twelve (12) inches from the gauge-planes of rails.

Where inner guard-timbers are employed, they shall be 6" X 8" on flat, dapped one (1) inch onto the ties, and placed so that their outer faces shall be just five (5) inches from the gauge-planes of rails.

Each guard-rail must be bolted to each alternate tie by a three-quarter (3/4) inch screw-bolt, the head of which shall be countersunk into the wood by means of a cup-shaped washer. Each guard-timber must be spliced over a tie with a half-and-half joint of at least six (6) inches lap, through which must pass a three-quarter (3/4) inch screw-bolt.

Guard-timbers shall extend over all piers and abutments.

Steel rails or heavy steel angles well fastened to the ties may be substituted for the inner wooden guard-rails, or the inner guards may be omitted altogether if the Engineer so direct.

RERAILING APPARATUS.

At each end of every bridge or trestle, there is to be placed a rerailing apparatus that will, in the most effective manner practicable, return to the track any derailed car or locomotive that is not more than half the width of track gauge out of line.