"Might as well connect the alternator?" said Tom interrogatively.

Jack nodded, and Tom threw a lever which brought the generator of
high frequency currents in contact with the motor by means of a
friction fly-wheel. The alternator began to buzz and spark, crackling
viciously.

A sort of metal helmet with two receivers attached to it, one on each
side, lay handy at Jack's hand. In front of him was the transmitter
joined to the metal box which contained the microphone, transformers
and inductance tuning coil. Tuning in the aërial apparatus was
effected by means of a small knob projecting through a slit in the
metal box enclosing the delicate instruments including the detector.
By working this knob the tuning block was moved up and down the coil
till a proper "pitch" was obtained.

Jack experienced an odd thrill as he prepared to send the first spoken
word ever exchanged between an airship in motion and a station on
land. He and Tom had sent plenty of wireless messages while soaring
through the ether, but somehow, the dot and dash system had not half
the fascination and mystery of the possibility of exchanging coherent
speech between land and air.

He placed his lips close to the receiver, and with his hand on the
tuning knob sent forth a loud, clear hail:

"Hullo, High Towers!"

There was no answer for a few seconds while he patiently adjusted the