"I have repeated all that it is necessary for you to know now," added the commander, as he took an orange from his pocket, and proceeded to show the difference between a great circle and any other. "You learned that all circles, whether great or small, even if no bigger than a nickel, contain three hundred and sixty degrees; and that every degree is divided into sixty parts called miles—geographical miles. These miles are the navigator's knots."
"Except the knots, the rest all comes back to me," said the lady. "But I don't understand the difference between a knot and a statute mile, as you call it."
"I can't say that I know much of anything about it," added Dr. Hawkes.
"A degree contains sixty-nine and a quarter miles, though the fraction varies with different authorities. Now, if you will divide 69.25 statute miles by 60," continued the captain, performing the operation on the back of an envelope, "the result will be 1.154 statute miles to a knot. The sixteen knots of this ship would therefore be nearly eighteen statute miles an hour."
"I think I understand it now, Captain Ringgold," said Mrs. Belgrave; and the others said the same.
"If we go as fast as that, we shall soon overtake the Maud," suggested Mrs. Woolridge.
"Not to-day, madam," replied the commander.
"When shall we catch up with her?"
"I told Captain Scott not to try to make more than ten knots an hour, which is very good sailing for a steamer of her size. She left at midnight, and is therefore twelve hours, or one hundred and twenty miles ahead of us."
"Knots or statute miles?" asked Mrs. Belgrave.