This was the first speaking-telephone that was ever constructed, so far as the writer is aware, but it was not a practicable instrument. Many sounds were not reproduced at all, and, according to the report of the judges at the Philadelphia Exposition, one needed to shout himself hoarse in order that he might be heard at all. THE AUTHOR'S TELEPHONE. For several years past my regularly recurring duties have taken me over the various subjects treated of in this book, and each one has been extensively illustrated in an experimental way, and a considerable number of new pieces of apparatus and new experiments to exhibit their phenomena have been devised by me. Among these, I would mention the following:-- 1. Measurement of the elongation of a magnetized bar. 2. A magneto-electric telegraph. 3. An electro-magnetic instrument for demonstrating the rotation of the earth. 4. The permanent magnetism of the magnetic phantom. 5. The convertibility of sound into electricity. 6. The induction of a vibrating magnet upon an electric circuit. 7. The origination of electric waves in a circuit by a sounding magnet. 8. The discovery of the action of the air in a sounding organ-pipe. 9. Two or three methods for studying the vibrations of membranes. 10. Lissajous forks for enlarged projections of sound vibrations. As soon, therefore, as I gave attention to the subject of telephony, I was able, with a few preliminary experiments, to determine the proper conditions for the transmission of speech in an electric circuit; and, without the slightest knowledge of the mechanism which Prof. Bell had used, I devised the following arrangement for a speaking-telephone. [Illustration: FIG. 14.--MY FIRST SPEAKING TELEPHONE.] [Illustration: FIG. 14.--END VIEW.]