The vision was there, clear and correct. But many problems of many kinds remained. A technical question that still loomed large concerned the matter of electrical induction. Both Michael Faraday in England and Joseph Henry in America had shown almost concurrently, a few decades earlier, that when a magnetized object is moved toward an electromagnet, a current is induced (generated) in the electromagnet’s coil; and when it is moved away from the electromagnet a current of the opposite kind is induced. (See “Professor Henry and His Philosophical Toys” in the December, 1963, AMERICAN HERITAGE.) It was this principle that Bell had invoked. But he wondered now if the current induced by his magnetized reed, vibrating over an electromagnet’s pole, would be strong enough to activate the receiver.

A problem of quite another variety now appeared. His financial backers in Boston, Hubbard and Sanders, were sponsoring his experiments in multiple telegraphy, and not his visionary notion of transmitting human speech by wire. Both men were convinced that success for all of them hinged on Bell’s ability to perfect and patent the harmonic telegraph with all possible speed. Western Union was stringing lines across the entire continent; it was overwhelmed with more messages than it could transmit; and, most alarming of all, other inventors were aware of the principle of the harmonic telegraph and were competing to win the race. Yet when Bell returned to Boston at summer’s end his thoughts were still dominated by the revelations of July. Moreover, he and Watson appeared to be making little progress toward their objective of evolving a workable harmonic telegraph. It continued to balk their best efforts. Night after night they labored vainly to persuade transmitters and receivers to vibrate in monogamistic resonance with their respective mates —and with no others. It seemed that however carefully they adjusted the tuning mechanisms, the pulses that cascaded along the wire overlapped each other in turbulent disarray.

One evening, as they sat down on a bench for a brief recess, Bell decided to take Watson into his confidence and inform him of his summer speculations. As Watson recalled the conversation in later years,
Bell said to me, “Watson, I want to tell you of another idea I have which I think will surprise you!” I listened, I suspect, somewhat languidly, for I must have been working that day about sixteen hours, with only a short nutritive interval . . . but when he went on to say that he had an idea by which he believed it would be possible to talk by telegraph, my nervous system got such a shock that the tired feeling vanished. I have never forgotten his exact words; they have run in my mind ever since like a mathematical formula. If,” he said, I could make a current of electricity vary in intensity, precisely as the air varies in density during the production of a sound, I should be able to transmit speech telegraphically.

Bell then took a piece of paper and made a sketch of his telephone transmitter as he envisaged it. They discussed it for a while and then went back to their labors on the harmonic telegraph. As Watson remembered later, they agreed that “the chances of its working were too uncertain to impress his financial backers . . . who were insisting that the wisest thing for Bell to do was to perfect the harmonic telegraph; then he would have money and leisure enough to build air castles like the telephone.”

Nevertheless Bell did muster up his courage a few days later. He approached Hubbard and Sanders and asked if they would care to sponsor his new conception. The answer was no. They saw no immediate need for such an instrument, while on the other hand there was a great demand for the harmonic telegraph and every urgent reason for bringing it to practical completion. Indeed, they exhorted Bell to hurry to Washington and register his specifications with the Patent Office.

Bell’s trip to Washington in February, 1875, proved a fateful one, for while he was in the capital he called upon Joseph Henry, dean of American physicists, inventor of the electric motor, and secretary of the Smithsonian Institution. In later years Bell spoke of this interview as a turning point in his career. For although the great physicist, then nearly eighty years old, listened with courteous interest while Bell described his harmonic telegraph, his interest turned to excitement when the young inventor went on to discuss his hopes of transmitting human speech over a wire. He told Bell that he had “the germ of a great invention” and urged him to forge ahead with his experiments. When Bell expressed fear that he lacked the electrical knowledge necessary to overcome the difficulties, Henry said laconically, “Get it!”

Four months elapsed between Bell’s conversation with Henry and the moment of enlightenment that forever afterward Bell and Watson would remember as the crucial episode of their collaboration. Those final months were not easy ones. Watson wrote later: