ilers provided with steam domes?

A. To furnish more steam space and to obtain dryer steam and to provide
a place for the safety valves, steam pipes, throttle valve and whistle.

28. Q. What must be the condition of a boiler to give the best results?

A. It must have good circulation and be clean and free from mud or
scale.

29. Q. What is meant by "circulation" in a boiler?

A. Free movement of the water, so that it may come in contact with the
heating surface and after being converted into steam be immediately
replaced by a fresh supply of water.

30. Q. What would be the effect if a "leg" of the fire-box became filled
with mud?

A. There would be no water in contact with the fire-box sheets and they
would quickly become overheated and mud-burned.

31. Q. What would be the result if the fire-box sheets became
overheated?

A. They would be weakened and forced off the staybolts and an explosion
would occur.

32. Q. Would it be advisable to put water into a boiler after the sheets
had become bare and red hot?

A. No. The fire should be killed at once.

33. Q. What effect has the stoppage of a large number of flues?

A. The heating surface and draft are decreased by just that much area.

34. Q. Why are boiler checks placed so far away from the fire-box?

A. To introduce the water into the boiler at as great a distance from
the fire-box as possible. This permits the water to become heated to a
high temperature before it comes in contact with the fire-box and also
improves circulation.

35. Q. What part of the boiler has the greatest pressure? Why?

A. The bottom, because it is subject to the weight of the water in
addition to the steam pressure in the boiler.

36. Q. What are the advantages of the extension front end?

A. To provide room for suitable draft and spark appliances.

37. Q. What is the purpose of a netting in a smoke-box or front end?

A. To act as a crusher of all cinders and prevent large cinders from
passing out of the front end to the atmosphere.

38. Q. What is the object of hollow staybolts?

A. To indicate when the staybolt is broken by the escape of steam
through the small hole in the bolt.

39. Q. What will cause the engine to tear holes in the fire?

A. Working hard or slipping when the dampers are open and the door
closed, or too thin a fire.

40. Q. Name the various adjustable appliances in the front end by which
the draft may be regulated.

A. The exhaust nozzle, t