“Of course not, but we’re loaded with coal, not ore, and coal isn’t as heavy as copper or iron.”
“It’s a good thing I’m the only one to hear you talk,” grinned Ted, “or I’d blush to think you were my brother. What’s the difference between the weight of thirteen thousand tons of coal and thirteen thousand tons of ore?”
The twinkle in Ted’s eyes caused Phil to hesitate, then continue: “Why, er, none, of course, but you needn’t be so cockey. A ton of coal takes more room than a ton of ore, so they couldn’t put thirteen thousand tons of coal aboard.”
“They could, too. If a boat’s capacity is thirteen thousand tons, she can carry thirteen thousand tons, whether it’s sawdust or mercury.”
“Not if the bulk is too great,” returned Phil. For several moments the brothers argued the problem, and then, as the first mate came in sight, Ted said:
“We’ll leave it to Mr. Adams.”
Readily Phil consented, and as the mate came up, they stated their opinions on the question at issue.
“Ted is right,” smiled Mr. Adams. “The point is this, while the coal fills the hold, because of its greater volume per unit, there is plenty of room in the hold after we have thirteen thousand tons of ore aboard because of its greater weight per unit. Why, if we should fill the Admiral with copper or iron ore, she’d sink like a plummet.”
“How do you know when she is loaded to her capacity—keep track of the tons?”
“That would be too difficult a task. The cars from which we load coal vary in the number of tons they carry, just as some of the ore pockets from which we load contain more ore than others. We save all trouble by loading until the keel is so many feet below the surface of the water, the tonnage carried varying in accordance with the depth of water over certain bars on our course and at the canal. On this trip we are only loaded to seventeen feet four inches. But as the water in the lakes is rising, when we come down we may be able to load to eighteen or nineteen feet.”