he instrument that was
there fixed, and, opening it, laid his finger on one of two small knobs
that it contained. The little bell that formed part of the instrument
at once started ringing--as did a similar bell in every room of the
ship--and so continued for about half a minute, when it ceased for about
two seconds, and then went on again.

"Good!" remarked the professor, removing his finger from the button, and
so stopping the ringing of the bell, as he drew out a small tube and
inserted it's end in one ear; "some one among our friends hears us."

Then he advanced his mouth to the mouthpiece, and spoke into it--

"Hillo! who are you?"

"I am Elphinstone," came the instant and clear reply. "Is that the
_Flying Fish_?"

"Yes," answered von Schalckenberg. "We are now at the village, and we
thought it an excellent opportunity to test the telephones. They appear
to answer perfectly; for I can hear you as distinctly as though you were
at my elbow. Can you hear me fairly well?"

"Splendidly; quite as well as you can hear me, I should say," replied
Sir Reginald. "I congratulate you, Professor, upon the success of your
latest invention. It is a most useful instrument; and I can easily
imagine a number of circumstances under which it might prove of the
utmost value to us. An idea has just occurred to me. How would it do,
while we are about it, to ascertain the greatest distance at which it is
possible to communicate intelligibly with each other?"

"Excellent!" answered von Schalckenberg. "We will shut ourselves in,
ascend to a height of ten thousand feet, into the calm belt, and then
proceed at full speed directly away from you. Keep your finger on the
black button of your instrument, please, for our guidance; and when our
bell ceases to sound we shall know that we have lost touch with you."

"Right!" came the answer. And instantly all the bells in the ship again
started ringing.

At the same moment the professor closed the door and windows of the
pilot-house, and injected a strong jet of vapour into the air-chambers,
causing the ship to rise rapidly into the air. Then he sent the engines
full speed ahead, and pointed the ship's sharp snout on a compass
bearing that left the party on the beach directly astern of her.

For three-quarters of an hour the bells in the ship continued to ring,
at first strongly, and then gradually with diminishing strength; and
finally, when the ship had been running continuou