‘These depend in great measure upon the volume of sound desired in the reproduction. If the reproduction is to be made audible to an assembly, considerable force is requisite in the original utterance; if for the individual ear, only the ordinary conversational tone (even a whisper has been reproduced). In both cases the original utterances are delivered directly in the mouthpiece of the instrument. An audible reproduction may, however, be had by speaking at the instrument from a distance of from two to three feet in loud tone. The application of a flaring tube or funnel to collect the sound waves, and the construction of an especially delicate diaphragm and embossing point, &c., are the simple means which suggest themselves to effect this.... ‘The foregoing presentment of the stage of development reached by the several essential features of the phonograph demonstrates the following _faits accomplis_: ‘1. The captivity of all manner of sound waves, hitherto designated as “fugitive,” and their retention. ‘2. Their reproduction with all their original characteristics, without the presence or consent of the original source, and after the lapse of any period of time. ‘3. The transmission of such captive sounds through the ordinary channels of commercial intercourse and trade in a material form, for purposes of communication. ‘4. Indefinite multiplication and preservation of such sounds, without regard to the existence or non-existence of the original source. ‘5. The captivation of sounds, with or without the knowledge or consent of the source of their origin... ‘The apparatus now being perfected in mechanical details will be the standard phonograph, and may be used for all purposes, except such as require special form of matrix, such as toys, clocks, &c., for an indefinite repetition of the same thing. The main utility of the phonograph being, however, for the purposes of letter-writing and other forms of dictation, the design is made with a view to its utility for that purpose. ‘The general principles of construction are, a flat plate or disk, with spiral groove on the face, worked by clockwork underneath the plate; the grooves are cut very closely together, so as to give a great total length to each length of surface--a close calculation gives as the capacity of each sheet of foil nearly 40,000 words. The sheets being but ten inches square, the cost is so trifling that but a hundred words might be put on a single sheet economically.... ‘The practical application of this form of phonograph is very simple. A sheet of foil is placed in the phonograph, the clockwork set in motion, and the matter dictated into the mouthpiece without other effort than when dictating to a stenographer. It is then removed, placed in suitable form of envelope, and sent through the ordinary channels to the correspondent for whom it is designed. He, placing it upon his phonograph, starts his clockwork, and _listens_ to what his correspondent has to say.’