Looking down, they saw mighty arms of polished, well-greased steel rise, swing slowly and descend rapidly on the other side. The huge rods of metal ascended and fell again with great rapidity, with a rhythmical, irresistible sweep that was fascinating to watch, making at each thrust and uplift a rushing, roaring noise like the simultaneous blows of a hundred sledge-hammers.
"A man was caught in there once," shouted the engineer, so as to make himself heard above the din. "It was just before the ship sailed. The poor fellow noticed that the crank needed oil, and thought he had time to do it before we started. Just as he was finishing, the signal 'Go ahead' came from the bridge. We didn't know he was in the pit, and we pulled the steam-chest lever. The massive arm rose. He shrieked. Before we could stop the machinery, it dropped again, and he was ground to pieces before our eyes."
Grace shuddered while the engineer calmly went on to explain the particular use of each part of the wonderful mechanism over which he had supreme control, speaking of each with as much affection as if it were his own offspring.
"Those cranks turn the shaft which gives the propellers their thousand revolutions a minute. The vibration you notice is caused by the enormous steam pressure. Two hundred pounds of steam pressing against every square inch of boiler surface represents power equal to the strength of 10,000 horses." Patting the head of the great beam as it rose to him, he added: "This is the best friend we've got—never tired, always true. But for this we should not be cutting through the water at the speed of twenty knots an hour."
Turning to an iron staircase on the left, he said:
"We'll go now to the boiler-room and see how we make the steam that gives life to the cylinders."
Beckoning them to follow, he disappeared down a steep stairway, spiral in form, which reached from the promenade-deck down to the very bottom of the vessel. The engineer gallantly extended his hand to assist Grace, and Professor Hanson, not quite sure himself of his footing, made a pretense of rendering similar service to Mrs. Stuart. Mr. Fitzhugh brought up the rear, stepping gingerly. Down they went, round and round, threading their way along an amazing labyrinth of valves, levers, gauges, eccentrics, tubes, and steam-pipes. They were now deep down in the bowels of the ship, a region with a sickening smell of machine-oil and steam. Down, down they went, past the coal-bunkers, following the engineer. The stairway being only imperfectly lighted by electric bulbs, they had to tread carefully. It grew perceptibly hotter. Presently they saw double rows of boilers set sideways. They were in the stoke-hold.
"Look out!"
The warning cry came from Mr. Wetherbee, who stopped short and held out his arms to prevent the visitors proceeding any farther. Then he shouted: "There are the furnaces! You'd better shade your eyes!"
There was a sudden glare which was almost blinding, a roar of flames under forced draught, and a wave of sickening heat. The air all at once became so thick with flying particles of coal that it was difficult to breathe. Choking, coughing, Grace and her companions clutched nervously at the slender guard-rail which alone interposed between the steel gallery where they stood and the inferno of smell, noise, and heat below.