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?