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 well make a vast difference in the success of a fireman, and a great many engine failures could be avoided by keeping the flues and grates in proper condition.

76.  Q. How should cab lamps, signal lamps, oil cans and lanterns be cared for?

A. They should be kept clean, free from leaks and always filled and ready for service before leaving terminals.

77.  Q. About how many drops in a pint of valve oil when fed through a lubricator?

A. About 4,500 drops.

78.  Q. Assuming that five drops per minute are fed to each of two valves and one drop per minute to the air pump, how many hours would be required to feed one pint of valve oil?

A. About eight hours.

79.  Q. Assuming that the engine is running twenty-miles per hour, how many miles per pint would be run?