me floating across the
water from the _Union_, and Douglas saw that she wished to attract his
attention to a signal which she had just hoisted.

He at once dived into the chart-house for the signal-book, and presently
he and his second lieutenant were poring over it in an effort to read
the communication. But, to Jim's intense annoyance, the signal, when
translated, seemed to have no meaning, and he realised that the corvette
was making a private and pre-arranged signal, which he was, of course,
unable to read.

"Confound it, Aranjuez!" he exclaimed, angrily, to his second
lieutenant, "what are we to do now? I did not anticipate this; and if
we are not careful he will take alarm and sheer off. I wish I had
thought of looking among the papers of the _Miraflores_' captain; they
might have contained the key to this private signal."

"Well, senor," replied the lieutenant, "we must delay making a signal of
any sort until the very last moment. Then, when he shows signs of
becoming suspicious and sheering off, we will hoist, very slowly, a
string of flags meaning nothing in particular. It will take him some
little time to decipher the flags; and we shall gain a few minutes while
he tries to fathom their meaning from his own private signal-book. We
ought, by that time, to be close enough to him for you to be able to
open fire effectively if the men will only keep calm and shoot straight.
Should we fail to disable him with the first few shots, however, he
will be off and we may be unable to catch him again."

"Precisely! This is the best--the only thing we can do, Aranjuez,"
replied Jim, gazing steadily through his telescope at the _Union_. "I
am not afraid of being unable to catch him if he will stick to deep
water; but I feel convinced that if he takes the alarm he will be
certain to run for shoal water at once. Have you got that bunting
ready?" he continued, "for, if so, we had better run up a string of
flags; he seems to be slowing down, as though he didn't altogether like
our looks. Quick! bend on and send them up. There, that's it--not too
fast now; not too fast. Ah, he has begun to move again, Aranjuez.
Don't hoist that signal any farther; if he only keeps as he is going for
another ten minutes he will be under our guns. Oh, good luck, good
luck! he's coming along at full speed, or I'm a Dutchman!"

Jim was right; the _Union_ was coming along at full speed; yet her
captain was not quite such a fool as th