The Edison phonograph monthly (Dec 1914-Dec 1915)

12 EDISON PHONOGRAPH MONTHLY, SEPTEMBER, 1915 inventions (requiring the making of many models and consuming years of time), this model worked the first time it was tried. Application for patent was executed Dec. 15, 1877, filed Dec. 24, 1877, and patent issued Feb. 19, 1878 — less than two months after filing date because the invention was so novel there was no chance of interference or infringement. During the busy days of the 80's, in which Mr. Edison invented the incandescent lamp, the carbon transmitter for telephones, the magnetic ore separator, built the first electric lighting system and generating station and the first electric railroad, besides taking out about 500 other patents, work on the phonograph was temporarily dropped. During this time Mr. Emil Berliner worked on and developed the lateral system of recording in contrast with the vertical system invented by Mr. Edison. In the vertical system, according to records published in 1890, a plate of metal is covered with a thin coating of wax. The recorder scratches through the wax, leaving the surface of the metal bare. Acid is then poured over the plate, etching the record into the metal. On account of the impossibility of obtaining a smooth etching such records have not come into general use, but have formed the basis for the lateral cut records, as used today. Before discussing the relative merits of the two systems it will be necessary to understand some of the musical and the mechanical principles involved. OVERTONES EXPLAINED Text-books on physics define sound for us and give us the rapidity of vibrations of the musical scale, stating that middle C, for example, is 256 vibrations per second. We know, however, that if several musical instruments were in another room so that they could be heard but not seen, we could distinguish between them though each sounded the same middle C. If the tone sounded were only 256 vibrations per second and, therefore, the same in each case, it would be impossible to distinguish between them. There is, therefore, a difference which enables us to distinguish one from the other, and this difference in the tone of each instrument is produced by the overtones, which are tones of higher frequency than the fundamental (in this case 256 vibrations per second), of which frequency the fundamental is always a mathematical multiple and which when combined with the fundamental gives the characteristic tone to each instrument or voice. If we pick up a comparatively light object we find that we can vibrate it with ease as compared with a relatively heavier object and the more rapidly we try to vibrate the object the more difficult it becomes. This is because of inertia. It is well known that if we wish to move a certain weight, a smaller rod is required to pull or push the weight than would be required if the rod is used as a fulcrumed lever. BERLINER VS. EDISON RECORDERS Comparing the Edison and Berliner recorders on disc recording, the diaphragm of the Edison recorder is fixed parallel and close to the wax disc and is directly attached to the sapphire stylus which engraves its motion in the wax. The Berliner recorder has its diaphragm at right angles to the wax disc, the vibrations of which diaphragm are conveyed to the wax through a comparatively long fulcrumed lever, one end of which is attached to the diaphragm and the other end arranged to engrave the wax. If this lever on a Berliner recorder is made comparatively light it will flex and bend to some extent rather than transmit the total swing of the vibration of the diaphragm to the wax, just as the tone of a Berliner type reproducer is diminished or softened when a thin needle is used to transmit the vibration from the record to the reproducer. If, on the other hand, this lever is made thick, its weight will increase and because of this increased weight it will be more difficult to vibrate or will tend to damp down these vibrations because of its inertia. In considering these sound or tone vibrations, we must recollect that the relatively low frequency fundamental will not suffer so much as the higher frequency or much more rapid overtones. Consequently such a recorder is capable of recording the pitch much better than the quality of music. This explains why such records reproduce the correct pitch of music but give the tones a sharp, phonographic quality rather than the full, rich, rounded quality of the original. In the Edison recorder the recording stylus is so directly fixed to the diaprahgm, which is close to the wax, and the moving parts are so light, because there is no lever action, but only a pushing strain on the member, that all of the delicate overtones are conveyed to the wax and are therefore reproduced with all the full, big, rich roundness of the original. In the Berliner records the sound waves are recorded on the sides of the grooves or the thinnest and weakest part. In the Edison records, the sound waves are at the bottom of the groove, or on the thickest and strongest part. It has, therefore, been found practicable to make Edison records with 150 threads to the inch, while Berliner