 It is a great pleasure to respond to this cordial invitation and to come to the Bell Telephone Laboratories and speak in this way about the days when Bell was working out his invention of the telephone. To do such a thing as this would have been not only impossible, it would have been inconceivable in the days when I was working with Mr. Bell. Motion pictures and talking motion pictures then were many years in the future, but here I am in the telephone shops again and again I hold in my hands some of the old instruments I made for Mr. Bell, now carefully preserved and treasured in the Bell System Historical Museum. I first met Alexander Graham Bell in 1874 when he came to the shop in Boston where I was working to have his harmonic telegraph constructed. The work was assigned to me. The object of this invention was the transmission of several telegraphic messages over one wire at the same time, utilizing the fact that a tuned reed will vibrate when its own note is sounded near it. This is a receiving instrument of Professor Bell's telegraph with its magnet and its steel reed. The sending instrument had a similar magnet and steel reed, but in addition it was provided with contact points so arranged that when its reed vibrated it would make and break the current from a battery, thus sending corresponding electrical impulses over the line to the distant receiving instrument. If the reed of that instrument were tuned to the pitch of these pulsations it would respond. I made for Bell six sending instruments with reeds of six different pitches and six receiving instruments with reeds to correspond. But the apparatus did not work satisfactorily when we tried it and in our many experiments with it where Bell was obliged constantly to retune the reeds. When doing this he had the habit of putting the receiving reed against his ear. This led to a most important discovery. During the months that we were working together on his telegraph Bell often spoke to me of another invention he had in his mind. It was the telephone. I remember my surprise when he first told me that he expected soon to be able to talk by telegraph, explaining to me his conception of an electric current that would copy the vibrations of speech. He had clearly thought out the scientific principle by which the electric transmission of speech was to be accomplished but he had not yet succeeded in devising the mechanism necessary to embody his conception in practical form. June 2nd 1875 is a most important day in the annals of the telephone for on that day guided by the light of his own wonderful theory Bell found the road leading to the realization of his speaking telephone idea. On that afternoon his harmonic telegraph was working very unsatisfactorily. I was in one room in charge of the transmitters as usual, one of the steel reeds stopped vibrating as I was snapping it to set it going again and told me he had heard in the instrument of his ear not only the pitch but also the overtones of the reed I had snapped. It was the first real sound that had ever been carried to a human ear by electricity for it was the first time the overtones of any sound had been so transmitted. The transmission of overtones is essential to the transmission of speech and Bell, this is the sound that Bell had always heard from the receiver when he had been listening before and this is the astonishing sound with the overtones he heard on June 2nd 1875. A person in the world, not even the greatest scientist, could have imagined that a piece of clock spring moved only by the feeble power of the voice could generate a current of electricity pulsating with the complex vibrations of any sound far less than that of human speech but the moment Bell heard the overtones of that spring he knew he had solved the problem of talking by telegraph on which he had pondered for years. After successfully repeating the experiment by vibrating over a magnet all the different steel springs we could find Bell sketched for me before we parted that night the first electric speaking telephone besieging me to have it ready to try the next evening if possible. Following his directions I constructed that first speaking telephone and had it ready for trial on the evening of the next day June 3rd 1875. Here is an exact duplicate of it. It has one of the telegraph receiving instruments at a cassette in a frame with a free end of its spring attached to the center of a drum head, an opening to project the voice against the other side of the drum head thereby forcing the reed to follow the voice vibrations instead of merely swinging to and fro. When we tried it I could recognize the sound of Bell's voice and could almost understand some of his words but my voice was not strong enough then to let him hear a sound. He was disappointed but nonetheless was sure he was on the right track. Many experiments on the telephone followed but it was not until March 10th 1876 that it transmitted its first complete sentence and proved it was a practical instrument for the everyday use of man. The circumstances of this achievement are interesting and significant. A few days before March 10th Bell had conceived the idea of the first battery transmitter ever devised and had given me directions for constructing it. In his first telephone the electric current was generated solely by the power of the voice but this new transmitter which I was to make for him was in principle the same as that in use today for the electricity was supplied by a battery leaving to the voice only the delicate work of impressing on that current its pulsations just as the touch of a hand can control a powerful engine. In order to utilize fully the voice vibrations the new transmitter was supplied with a mouthpiece about five inches in diameter. This new mouthpiece turned out to be an important element in the first test we made of the new instrument. On the evening of March 10th 1876 Bell sat in front of the new transmitter in the back room which I had made into a laboratory for him on the top floor of number five exit her place Boston and I went down the hall to the front room to listen for the results with a telephone receiver. But as Bell was about to speak in the new instrument a motion of his arm upset over his clothes a battery jar of a situated water. In the excitement of the accident Bell called out to me Mr. Watson come here I want you. The big mouthpiece picked up his call for help and I heard every word of it through the receiver at my ear. The new transmitter was better than we had expected or had dared hope. Bell forgot the accident in his joy over the success of the test that filled the entire evening. He had brought his great invention to the point where its future was assured. And this first sentence ever sent through the telephone although apparently very common place was really highly significant for the telephone today renders no service more vital than in times of emergency. And the first message it ever transmitted was unquestionably an emergency call.