Pinholes in eye-bars must be in the centre of the heads, and on the centre line of the bars.

Bars, which are to be placed side by side in the structure, shall be bored at the same temperature, and shall be of such equal length that, when placed in a pile, the pin at each end will pass through the holes at the same time without forcing.

PINS.

All pins shall be turned accurately to a gauge, and shall be finished perfectly round, smooth, and straight. All pins up to three and one-half (3 1/2) inches in diameter shall fit the pinholes within one fiftieth (1/50) of an inch, and all pins over three and one-half (3 1/2) inches in diameter shall fit their holes within one thirty-second (1/32) of an inch.

The Contractor must provide steel pilot-nuts for all pins to preserve the threads while said pins are being driven.

TURNED BOLTS.

When members are connected by bolts which transmit shearing-stresses, the holes must be reamed parallel, and the bolts must be turned to a driving fit.

TURNBUCKLES, NUTS, THREADS, AND WASHERS.

All sleeve-nuts, turnbuckles, and clevises must be made so strong and stiff that they will be able to resist without rupture the ultimate pull of the bars which they connect, and without distortion the greatest twisting force to which they could ever be subjected. They must be made so that the threaded lengths of the rods engaged can be verified.

The dimensions of all square and hexagonal nuts, except those on the ends of pins, shall be such as to develop the full strength of the body of the adjustable member. No round-headed bolts will be allowed.

Washers and nuts must have uniform bearing.

Cast or wrought iron washers must be used under the heads of all timber bolts when the bearing is on the wood.