rk more satisfactorily
than the type they now had. But in spite of their many experiments they
came back to the kind of instrument with which they had started,
discovering nothing that was superior to their original plan. Except
that they compelled the transmitter to do double duty and act also as a
receiver, the telephone that emerged from these many tests was
practically similar in principle to the one of to-day."

"Had they made any long-distance trials up to this time?" questioned
Laurie.

"No," Mr. Hazen admitted. "They had lacked opportunity to make such
tests since no great span of wires was accessible to them. But on
October 9, 1876, the Walworth Manufacturing Company gave them
permission to try out their device on the Company's private telegraph
line that ran from Boston to Cambridge. The distance to be sure was
only two miles but it might as well have been two thousand so far as
the excitement of the two workers went. Their baby had never been out
of doors. Now at last it was to take the air! Fancy how thrilling the
prospect was! As the wire over which they were to make the experiment
was in use during the day, they were forced to wait until the plant was
closed for the night. Then Watson, with his tools and his telephone
under his arm, went to the Cambridge office where he impatiently
listened for Mr. Bell's signal to come over the Morse sounder. When he
had heard this and thereby made certain that Bell was at the other end
of the line, he cut out the sounder, connected the telephone he had
brought with him, and put his ear to the transmitter."

The hut was so still one could almost hear the breathing of the lads,
who were listening intently.

"Go on!" Laurie said quickly. "Tell us what happened."

"_Nothing happened!_" answered the tutor. "Watson listened but there
was not a sound."

"Great Scott!"

"The poor assistant was aghast," went on Mr. Hazen. "He was at a
complete loss to understand what was the matter. Could it be that the
contrivance which worked so promisingly in the Boston rooms would not
work under these other conditions? Perhaps an electric current was too
delicate a thing to carry sound very far. Or was it that the force of
the vibration filtered off at each insulator along the line until it
became too feeble to be heard? All these possibilities flashed into
Watson's mind while at his post two miles away from Mr. Bell he struggled
to readjust the instrument. Then suddenly an inspirati