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234 sound, and we cannot expect it, "when further developed by study, to do for us, with regard to faint sounds, what the microscope does with matter too small for human vision."

We cannot correctly regard the sound heard in the telephone receiver as "a magnified image" of the original vibrations; for, while the fundamental tone is reproduced with considerable accuracy, the harmonics or overtones, giving the timbre, or individuality to the sound, are in most cases very imperfectly rendered.

2. If the ear is placed in as favorable a position to hear the original faint vibrations (which jar the delicately-poised piece of carbon) as it is when listening to the telephone, it will be found that the increased volume of sound issuing from the diaphragm of the receiver is more imaginary than real.

For these, and other reasons, the writer is of the opinion that the probable future value of this discovery has been greatly exaggerated, and that it is likely to prove an addition to the rather plentiful crop of scientific green fruit which fails to ripen into the full perfection so enthusiastically predicted by the luxuriance of the blossoms.



OTHING is more natural than that there should be great expectations in the non-scientific mind in regard to what electricity is destined to do for the world in future—expectations which, on the one hand, are grounded in reason, and, on the other, are liable to the most extravagant exaggeration. The marvelous things already accomplished by means of this mysterious agent, as made familiar in the electro-chemical industries, the telegraph, telephone, and electrical illumination, have a tendency, of course, to prepare the mind to look for further unusual and astonishing results. Just now a revolution in illumination is widely anticipated, by which the common illuminants will be superseded in the daily life of the people, through improvements in the electrical light. The probability of this important result is greatly increased, and is, indeed, supposed to have become a certainty, because electrical illumination is already an established fact on a large scale, it having been used in lighthouses for years, and successfully introduced into factories, depots, theatres, and other places where large spaces are to be illuminated. So much—the main thing, and apparently everything—being actually gained as a fact of experience, the carrying out of the invention into minor details is taken as a foregone conclusion. In this state of the public mind the announcement of Mr. Edison—the foremost inventive genius of the age—that he had actually solved the problem which would make electric illumination available for common household uses, was generally accepted as a matter of course, and sent a tremor through the gas-stocks of the world. Nevertheless, the desideratum has not yet been reached, and, for aught that actually appears, we are no nearer this important consummation than we were twenty years ago.

It may be well to remind the sanguine believers in this unquestionably most desirable improvement, of the analogous excitement there was, some thirty or forty years ago, in regard to electricity as a motive power. A new source of mechanical energy had been discovered in electro-magnetism, which was developed by appropriate machinery, so as to be capable of doing all kinds of work. There was the accomplished fact, and buzz-saws were driven through two-inch planks, before astonished audiences, merely by batteries in the cellar, connected with the working-machine by conducting wires. The steam-engine was threatened, and we seemed to be on the eve of a new epoch in the use of motive powers.