“Willis!  Willis!” cried Jack, “I shall tell Sophia.”

But there was neither the soft voice there, the caressing hand, nor the sweet fascination of the young girl’s presence, and Willis continued immovable.

Becker saw that his was one of those minds that grew less calm the more they were urged, and the excitement of which must be permitted to wear itself out; he therefore beckoned his sons to leave him to his own reflections.

The wind still blew a gale, and the pinnace pitched heavily; but the sun was now beginning to break through the masses of lurid cloud, and the air was becoming less and less charged with vapor.

“I can descry nothing either,” said Becker; “and yet this is the direction the storm must have driven the sloop.”

“The sea is very capricious,” suggested Fritz.

“True, but not to the extent of carrying a ship against the wind.”

“Unfortunately,” said Jack, “it is not on sea as on land, where the slightest indications of an object lost may lead to its discovery; a word dropped in the ear of a passer-by might put you on the track, but here it is no use saying, ’Sir, did you not see the Nelson pass this way?’”

“Fire a shot,” said Ernest; “it may perhaps be heard, now that the air is less humid.”

The two-pounder was ready charged; Fritz struck a light and set fire to a strip of mimosa bark, with which he touched the piece, and the report boomed across the waters.

Willis raised his head and listened anxiously, but soon dropped it again, and resumed his former attitude of hopeless despair.

“It may be,” said Ernest, “that the Nelson hears our signal, though we do not hear hers.”

“How can that be?” inquired Jack.

“Why, very easily.  Sound increases or diminishes in intensity according as the wind carries it on or retards it.”

“What, then, is sound, that the wind can blow it about, most learned brother?”

“It is a result of the compression of the air, that from its elasticity extends and expands, and which causes a sort of trembling or undulation, similar to that which is observed in water when a stone is thrown into it.”

“And you may add,” said Becker, “that bodies striking the air excite sonorous vibrations in this fluid; thus it rings under the lash that strikes it with violence, and whistles under the rapid impulsion of a switch:  it likewise becomes sonorous when it strikes itself with force against any solid body, as the wind when it blows against the cordage of ships, houses, trees, and generally every object with which it comes in contact.”

“I can understand,” replied Jack, “how this sonorous effect is produced on the particles of air in immediate contact with the object struck; but how this sound is propagated, I do not see.”

“Very likely; but still it travels from particle to particle, in a circle, at the rate of three hundred and forty yards in a second.”