e wheels and axles are of wrought iron, and the tires of the wheels
are of steel. The driving wheels are 6 feet 6-1/2 inches in diameter, and
the diameter of crank pin is 3-1/2 inches. The diameter of the smaller
wheels is 48-1/2 inches. The axle boxes are of cast iron with bushes of
Fenton's metal, and the leading axle has four bearings. The springs are
formed of steel plates, 3 feet long, 4 inches broad, and 1\2 inch thick.
The axle of the driving wheel has two eccentrics, forged solid upon it, for
working the pumps.

661. _Q._--Will you specify the dimensions of the principal parts of the
engine?

_A._--Each of the cylinders which is 14-1/4 inches diameter, has the valve
casing cast upon it. The steam ports are 13 inches long and 1-5/8 inches
broad, and the exhaust port is 2-1/2 inches broad. The travel of the valve
is 4-1/8 inches, the lap 1 inch, and the lead 1/4 inch. The piston is 4
inches thick: its body is formed of brass with a cover of cast iron, and
between the body and the cover two flanges, forged on the piston rod, are
introduced to communicate the push and pull of the piston to the rod. The
piston rod is of iron, 2-1/2 inches diameter. The guide bars for guiding
the top of the piston rod are of steel, 4 inches broad, fixed to rib iron
bearers, with hard wood 1/4 of an inch thick, interposed. The connecting
rod is 6 feet long between the centres, and is fitted with bushes of white
metal. The eccentrics are formed of wrought iron, and have 4-1/8 inches of
throw. The link of the link motion is formed of wrought iron. It is hung by
a link from a pin attached to the framing; and instead of being susceptible
of upward and downward motion, as in the case of the link represented in
fig. 57 a rod connecting the valve rod with the movable block in the link,
is susceptible of this motion, whereby the same result is arrived at as if
the link were moved and the block was stationary. One or the other
expedient is preferable, according to the general nature of the
arrangements adopted. The slide valve is of brass, and the regulator
consists of two brass slide valves worked over ports in a chest in the
steam pipe, set in the smoke box. The steam pipe is of brass, No. 14. wire
gauge, perforated within the boiler barrel with holes 1/12th of an inch in
diameter along its upper side. The blast pipe, which is of copper, has an
orifice of 4-1/4 inches diameter. There is a damper, formed like a Venetian
blind, with the plates