is knocked out.

66. Q. Is warm water in the tank of any advantage in making steam
rapidly?

A. Yes; careful experiments have shown that a locomotive will generate
one per cent. more steam for every eleven degrees that the tank water is
heated; thus by heating the feed water in the tank from 39 degrees to 94
would effect a saving of five per cent.

67. Q. Then why not heat the feed water to the boiling point (212
degrees)?

A. If the feed water is heated much above 100 degrees it will not
condense enough steam in the injector to cause it to work properly. Some
injectors will work hotter water than others. It would also spoil the
paint on the tank if heated to a much higher temperature.

68. Q. At 200 pounds pressure per square inch, what is the pressure per
square foot on the sheets of a boiler?

A. About fifteen tons.

69. Q. What is the total pressure on the fire-box of a large
locomotive?

A. Over 3,000 tons.

70. Q. Give a practical definition of heating surface.

A. The heating surface of a boiler includes all parts of the boiler and
tubes that are directly exposed to fire or heat from the fire and are
surrounded by water.

71. Q. Should an engine be slipped to get water out of the cylinders or
steam passages?

A. No; the water should be worked out by opening the cylinder cocks and
starting the engine slowly.

72. Q. What does it indicate when the smoke trails back over the train
and into the coaches after shutting off?

A. It indicates poor firing or a lack of understanding between the
engineer and fireman in regard to where the engine was to be shut off.

73. Q. Before shaking grates or dumping the ash-pan, what should be
observed?

A. That the engine is not passing over bridges or cattle guards,
crossings, switches, interlocking fixtures, or in yards. Fire on the
track should be extinguished promptly at places where ash-pans are
cleaned.

74. Q. Which is easier and more satisfactory on a long run, to stop and
clean the fire if necessary or to continue to the end of a long, hard
trip with a dirty fire?

A. Stop and clean the fire if necessary. It will save fuel and labor
during the remainder of the trip and may also save an engine failure.

75. Q. Should you examine the flues to see if they are stopped up and
leaking, and inspect the grate and grate rigging carefully before
leaving the engine at a terminal?

A. Yes, so they can be reported if necessary. Clean flues and grates
working