for use on shipboard. So these experiments also developed
no practical improvement in the existing means of communication. But
Professor Trowbridge had demonstrated new possibilities, and had set
men thinking along new lines. He was the pioneer who pointed the way
to a great invention, though he himself failed to attain it.

Bell followed up Trowbridge's suggestions of using the water as a
medium of communication, and in a series of experiments conducted on
the Potomac River established communication between moving ships.

Professor Dolbear also turned from telephone experimentation to the
search for the wireless. He grounded his wires and sent high currents
into the earth, but improved his system and took another step toward
the final achievement by adding a large induction coil to his sending
equipment. He suggested that the spoken word might be sent as well as
dots and dashes, and so sought the wireless telephone as well as
the wireless telegraph. Like his predecessors, his experiments were
successful only at short distances.

The next application of the induction telegraph was to establish
communication with moving trains. Several experimenters had suggested
it, but it remained for Thomas A. Edison to actually accomplish it.
He set up a plate of tin-foil on the engine or cars, opposite the
telegraph wires. Currents could be induced across the gap, no matter
what the speed of the train, and, traveling along the wires to the
station, communication was thus established. Had Edison continued his
investigation further, instead of turning to other pursuits, he
might have achieved the means of communicating through the air at
considerable distances.

These experiments by Americans in the early 'eighties seemed to
promise that America was to produce the wireless telegraph, as it had
produced the telegraph and the telephone. But the greatest activity
now shifted to Europe and the American men of science failed to push
their researches to a successful conclusion. Sir W.H. Preece,
an Englishman, brought himself to public notice by establishing
communication with the Isle of Wight by Morse's method. Messages were
sent and received during a period when the cable to the island was
out of commission, and thus telegraphing without wires was put to
practical use.

Preece carried his experiments much further. In 1885 he laid out two
great squares of insulated wire, a quarter of a mile to the side,
and at a distance of a quarte