of the phonograph, in which a single mouthpiece with diaphragm and stylus serves the purpose both of recorder for making the record and a speaker for reproducing it, a trumpet or horn being used, as indicated in dotted lines, to concentrate the vibrations in recording and to augment the sound in reproducing. [Illustration: FIG. 190.--SECOND FORM OF PHONOGRAPH.] The phonograph is in reality a development of the phonautograph, which was an instrument invented by Leon Scott in 1857 to automatically record sounds by diagrams. There is a model of Scott’s phonautograph in the National Museum at Washington, D. C, and it consists of a chamber to catch the sound waves and an elastic diaphragm with stylus working on a revolving cylinder bearing a sheet of paper coated with lampblack. The phonograph’s record-making mouthpiece, with its diaphragm and stylus, is substantially a phonautograph, but instead of simply causing the stylus to trace a record on carbon-coated paper and stopping with this result, Edison traced a record in a substance--tinfoil--which was capable of mechanically translating that record into sound again by a mere reversal of the function of the stylus and diaphragm. This was the very essence of simplicity and logical reasoning. All records had been heretofore traced for visual inspection only. Edison’s record was not for visual inspection, but was endowed with the mechanical function of reproducing sound. From the first Edison believed that his phonograph was to fill an important place in the business activities of the world, since here seemed a silent but faithful stenographer which reproduced the words of the speaker with absolute fidelity, even to the quality of emphasis and inflection, and which made no mistakes, was always even with the speaker in its work, and asked no questions. For a number of years, however, the invention lay dormant and served no other purpose than that of a scientific curiosity or an amusing toy. The difficulty of its practical application largely existed in the perishable form of the record, which, being in tinfoil, was liable to be mutilated and distorted, and was not well adapted for storage or transportation. A few years after the announcement of Mr. Edison’s invention. Dr. Alexander Graham Bell, the distinguished inventor of the telephone, with his associates, Messrs. Chichester A. Bell and Charles Sumner Tainter, directed their attention to the improvement of the phonograph. Dr. Bell had received from the French government, upon the recommendation of the French Academy of Sciences, the Volta prize of 50,000 francs as a recognition of his successful work in acoustics and the invention of the telephone, and with this sum he built the Volta Institute in Washington and carried on the work of developing the phonograph.