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?