For two hours they examined and talked of mechanism for ships and mills, and they even ventured to guess what the earth’s motive power might be.  It was now five minutes of midnight.  The chief furnished Ingram an oversuit and the young engineers dropped through manholes and down vertical and spiral ladders into the cellar of the steamer, the bottom of which was thirty feet below the water level.

“The ‘Campania,’” said Siemens, “has a strong double bottom that forms a series of water-tight compartments which, filled with water, furnish ballast when necessary.  On the second steel or false bottom of the steamer, fore and aft, are located the boilers, furnaces, and coal-bunkers.  We have fourteen double-ended boilers, fitted longitudinally in two groups, in two water-tight compartments, and separated by huge coal-bunkers.  Each boiler is eighteen feet in diameter and seventeen feet long.  The thickness of the steel boilerplate is 1-17/32 inches.  Above each group of boilers rises 130 feet in height a funnel nineteen feet in diameter, which, if a tunnel, would easily admit the passage of two railway trains abreast.”

George saw the fires lighted, and when the furnaces required more coal, suddenly a whistle brought fifty stokers or firemen, the automatic furnace doors flew open, and a gleam of light flooded everything.  Long lances made draft-holes in the banks of burning coal, through which the air was sucked with increasing roar.  The round, red mouths of the hundred craters snapped their jaws for coal, which was fed them by brawny men whose faces were streaked with grimy perspiration, and their bodies almost overcome by heat.  The hundred furnaces are kept at almost white heat from New York to Liverpool.

“Four hours on, and four hours off, and the best quality of food are some of the recent improvements,” said Siemens.

George Ingram shook his head, and his heart ached as he witnessed the stokers, and resolved to do his utmost to mitigate the hardships of labor.  “What are the duties of the stokers?” inquired George.

“Our stokers,” replied Siemens, “must be men of strength and skill, for they both feed and rake the fires.  The ashes and slag must be hoisted and dumped into the ocean, and twice an hour, as the gauges indicate, fresh water is let into the boilers.  Daily the boilers convert into steam over a hundred tons of water, which, condensed, is used over and over again.”

“What quantity of coal do you use?”

“About three hundred tons per day, or an average of nearly two thousand tons per voyage.  The coal carrying capacity of the “Campania,” however, when needed as an armed cruiser, can be greatly increased.”

Siemens led Ingram to see the gigantic cranks, and propeller shafts.  Each of the several cranks is twenty-six inches in diameter and weighs 110 tons; the shafts made of toughest steel are each twenty-four inches in diameter, and each weighs over 150 tons.  The propellers are made of steel and bronze, and each of the six blades of the two screws weighs eight tons.  It was now past two o’clock and George thanked Mr. Siemens and said he should be pleased to examine further his department when at sea.  It was past three o’clock when George turned off his gas at the hotel.