spring tide to-day," remarked Thornton.

"Hello, boy!" exclaimed the Captain; "are you a sailor?"

"Oh no, sir," said Thornton. "I don't know one sail from another, but I
know the age of the moon, and I know it's time for the spring tides
here."

"Well, even that's worth knowin'," said the Captain, "and if you keep
your eyes open while you're aboard here, you'll learn a lot of other
useful things."

"It will be funny to see Thornton learning _useful_ things," exclaimed
Mrs. Seabury.

"Let the boy alone, mother," said Mr. Seabury, "he'll come out all
right."

In the afternoon the schooner got under way, with a fine westerly
breeze abeam, and stood out to sea. As she passed the lighthouse at the
entrance to the little harbor, the Captain took certain bearings of it
with his compass, while Thornton stood by and watched him with interest.

"I suppose you are fixing the schooner's position by bow-and-beam
bearings," said the boy.

"That's what I'm doin'," said the Captain; "but how'd you know anything
about them?"

"Oh, I've heard of them," said Thornton, modestly.

"Well, come and see me set the patent log," said Captain Whitby.

Thornton seemed to know something about that too, and the Captain
decided that although the boy might have a good deal of useless
knowledge in his head, he had hold of some facts worth knowing. He said
as much to Mrs. Seabury, but she replied:

"What's the good of his knowing those things? He isn't a sailor."

"That's true enough," answered the Captain, remembering that the boy did
not know one sail from another.

By six o'clock the schooner was well out to sea, and as it grew dark the
Captain came on deck with his sextant. Thornton became intensely
interested.

"Going to take Jupiter for latitude, Captain?" he asked.

"That's what," was the reply; "but what do you know about it?"

"Oh, I'm not so ignorant that I can't tell what latitude and longitude
are," said Thornton; "and I know that Jupiter will be on the meridian at
8.32 to-night."

"Well, then, you know some more things that are worth knowin' to a
sailor-man, anyhow," declared Captain Whitby.

For twenty-four hours the schooner glided along slowly and quickly, the
wind constantly drawing ahead and forcing her off her course. Then it
fell dead calm, and a heavy swell began to roll in from the southeast.

"Mother," said Thornton, "don't be frightened, but we're going to have a
storm."

"Mercy sakes!" exclaimed Mrs