leet might escape a severe handling, but otherwise that the guns of San
Lorenzo, if well served, might sink or damage every ship in the
squadron. Indeed, the deep-water channel, down which the ships must
pass, was only about three hundred yards from the guns of the enemy, and
which from their elevation could send a plunging fire directly down on
their decks.

In front of the batteries, about twelve hundred yards from them, was one
of an archipelago of islands, extending for some miles along the eastern
or Entre Rios shore of the river, covered with trees, brushwood, and
reeds. The passages between these islands and the eastern shore were
much too shallow for the navigation of vessels of any size. Of
necessity, therefore, the whole fleet had to pass under the high cliff
of San Lorenzo, crowned by its formidable batteries. The skippers of
the merchantmen were quaking in their shoes, believing that the
men-of-war must be sent to the bottom and effectually block up the
channel, so that they would be caught in a trap and fall into the hands
of the tyrant Rosas.

All sorts of reports were flying about; some said that one hundred heavy
guns were planted on the top of the cliffs, and that red-hot shot and
missiles of all sorts would be showered down on them, but still the
commodore kept the plan he proposed to adopt secret. The officers of
the men-of-war, however, felt confident that whatever it was, it would
most likely succeed.

Terence had returned to his ship: Jack was now alone. He was seated in
his cabin, when a lieutenant from one of the steamers came on board:--

"Come, Rogers, you are wanted by the commodore, as you are not only to
be let into the secret of the plan, but to assist in carrying it out."

Jack, highly delighted, jumped up, and buckling on his sword accompanied
his brother officer on board the flagship.

The expedition was immediately to start to examine the island in front
of the batteries. The plan was simple in the extreme, should shelter be
found on the island, it was proposed to plant a rocket battery behind
it, and as the ships came down to throw up showers of rockets into the
fort, so as to drive the Spaniards from their guns till the whole fleet
had passed.

Evening was drawing on, the boat was ready, the English and French
commodores, Lieutenant Mackinnon, the designer of the scheme, Jack, and
several other officers went in her. The oars were muffled, nothing was
said above a whisp