necessary to remove it, what should you do?

A. Remove the broken piston valve, reduce boiler pressure to 100 pounds
and proceed.

26. Q. What is the difference between a Vauclain four-cylinder compound,
a four-cylinder tandem, a balanced and a Mallet compound in their
arrangement of cylinders?

A. A Vauclain compound has two cylinders on each side, one above the
other, and both piston rods connected to one cross-head. A four-cylinder
tandem has four cylinders, the high pressure being ahead of the low
pressure on each side, and both pistons connected to one piston rod and
one cross-head. A balanced compound has four cylinders, the two
high-pressure cylinders being between the frames, each having a main rod
connected to a crank axle. The two low-pressure cylinders are located
outside the frame, each having a main rod and crank pin connected to
the driving wheel center. A Mallet compound consists of two separate and
independent engines, one fixed to the boiler, the other swinging from a
center and sliding back and forth under the front end of the boiler. The
rear engine works steam at high pressure; steam from this engine
exhausts through a receiver pipe having flexible joints to the forward
engine which works the steam at low pressure, then exhausts it to the
front end and stack.

27. Q. How many main steam valves has each type?

A. The Vauclain has one valve on each side, distributing steam to the
high and low-pressure cylinder on that side. The four-cylinder tandem
has two valves on each side, one for each of the two cylinders. A