In the meantime, the Tampico, from hold to masthead, was blazing like a tall Sound steamboat.  Dan gained the bridge and gazed at the illumination with a smile; for all this splendor of electrical display was for a purpose.

“You’ve locked them in, eh?” said Mr. Howland, abruptly.  He had been pacing the bridge, the victim of many doubts.

“Yes,” replied Dan; and there was a sharp inflection in the monosyllable which precluded further questioning.  The owner had instructed his Captain to land the guns which were lying in the hold of the steamship, and the young Captain was intent on the matter in hand.

He pulled a certain crank, upon which the steam winches began to revolve with ghostly creakings, bringing the anchor up out of the mud.  Then he signalled for full speed ahead.  There was a creaking, a sound of roiling water, and then, still blazing with light, the steamship made out for the open sea.

They had gone but a quarter of a mile when those who were left on the fleet suddenly came to a realizing sense of the diabolical plot hatched under their very noses.  A gun boomed, a six-pounder shell squealed past the bridge, but the Tampico slipped on her way seaward, while the funnels of the fleet belched clouds of smoke blacker than the velvet skies.  From the saloon came muffled shouts and ineffectual poundings on the bulkhead doors.

“The walls are good and thick,” said Dan, grimly.  “I doubt they will be heard—­unless some one of the craft gets within a hundred yards of us.  They ought to have full steam up by this time.  I might as well stop her right here; this is about right.”

As the steamship swung heavily on the tide, the Captain shouted an order, which was taken up on deck and carried down a hatchway.  The next instant the lights in the lower part of the hull went out.  A few minutes later, another stratum of lights disappeared, and still later the deck lights.  Then out went the port and starboard lamps.  Then there was a ten-minute wait, while Mr. Howland, Virginia, and the rest of the party who had ventured on deck, thrilled and delighted with the situation, held their breath.  Dan pulled another switch and the masthead lights went out.  The Tampico was now a part of the night.

“Oh!” exclaimed Virginia, “I see.  You have given them an imitation of a vessel disappearing hull down in the darkness.  How clever!”

An exclamation from Mr. Howland broke the silence.  “Oh!” he cried.  “I see.”  And he placed his hand on Dan’s shoulder.

The stillness was intense.  The water swept softly past the hull; the extremities of the vessel were lost in a blur of black.  Mr. Howland became impatient.

“What can be the matter with those fellows?  Why don’t they chase us and be done with it?”

Dan touched him on the shoulder.  From the outer darkness floated a mysterious bourdon, which rapidly outgrew that definition and became a veritable commotion.  One light twinkled, then another, and still another.  Finally the swift pulsation of engines at high pressure rived the night.