In the English scientific journal Engineering, of June 21, 1878, appears a six column article on "Edison's Carbon Telephone," illustrated with ten engravings from Mr. Prescott's recent work on "The Speaking Telephone, Talking Phonograph, and other novelties." The descriptions of the cuts, and the rest of the information given, so far as correct, obviously come from the same source.
So far as correct: unhappily for the honor of scientific journalism, the writer's desire is plainly not so much to do justice to truth as to exalt Mr. Hughes at the expense of Mr. Edison. To this end he has studiously suppressed from Mr. Prescott's description of the carbon telephone the points which establish Mr. Edison's claim to the prior invention or discovery of everything involved in Mr. Hughes' microphone, while he has as studiously dwelt upon those same points as constituting the peculiar merits of Mr. Hughes' work.
For example, while he uses Fig. 21 of Mr. Prescott's book, he leaves out the very important little diagram numbered 20. It represents one form of the apparatus to which Sir William Thomson refers in the letter in which he says:
"It is certain that at the meeting of the British Association at Plymouth last September, a method of magnifying sound in an electric telephone was described as having been invented by Mr. Edison, which was identical in principle and in some details with that brought forward by Mr. Hughes."
The figure looks altogether too much like one form of Mr. Hughes' microphone to allow of its use in an article intended to establish the novelty of Mr. Hughes' discovery.
The omissions from the text are quite as significant. Under the first cut used in Engineering, Mr. Prescott says: "In the latest form of transmitter which Mr. Edison has introduced the vibrating diaphragm is done away with altogether, it having been found that much better results are obtained when a rigid plate of metal is substituted in its place.... The inflexible plate, of course, merely serves, in consequence of its comparatively large area, to concentrate a considerable portion of the sonorous waves upon the small carbon disk or button; a much greater degree of pressure for any given effort of the speaker is thus brought to bear on the disk than could be obtained if only its small surface alone were used."
The Engineering writer coolly suppresses this important statement. He does worse: he puts in its place the false statement that "the essential principle of Mr. Edison's transmitter consists in causing a diaphragm, vibrating under the influence of sonorous vibrations, to vary the pressure upon, and therefore the resistance of, a piece of carbon," and so on.
A little further on, while repeating Mr. Edison's account of the experiments which led to the abandonment of the vibrating diaphragm (page 226 of Mr. Prescott's book), the Engineering writer drops out the following remark by Mr. Edison: "I discovered that my principle, unlike all other acoustical devices for the transmission of speech, did not require any vibration of the diaphragm—that, in fact, the sound waves could be transformed into electrical pulsations without the movement of any intervening mechanism."
Worse yet, in the very face of Mr. Edison's assertion to the contrary—an assertion which he could not by any possibility have overlooked—this most unscientific journalist says: "Mr. Edison finds it necessary to insert a diaphragm in all forms of his apparatus, that being the mechanical contrivance employed by which sonorous vibrations are converted into variations of mechanical pressure, and by which variations in the conductivity of the carbon or other material is insured.... On the other hand, Mr. Hughes employs no diaphragm at all, the sonorous vibrations in his apparatus acting directly upon the conducting material or through whatever solid substance to which they may be attached."
In this way throughout the offending article, the writer persistently robs Edison to magnify Hughes, giving credit to Mr. Hughes for exactly what he has suppressed from Mr. Prescott's book. To insist as he does, that, because Mr. Edison covers his carbon button with a rigid iron plate, in his very practical telephone, therefore a vibrating diaphragm is an essential feature of Mr. Edison's invention, is a very shallow quibble in the face of Mr. Edison's and Mr. Prescott's statements that the carbon button acts precisely the same in the absence of such covering, though not so strongly. Mr. Edison's laboratory records show a great variety of experiments in which the carbon was talked against without "any intervening mechanism." In a telephone for popular use, however, to be held in the hand, turned upside down, talked into, exposed to dust and the weather, it was obviously necessary to use some means for holding the carbon in place, and to prevent its sensitiveness from being destroyed by dirt and the moisture of the breath when in use. For this purpose a rigid iron partition seemed at once convenient and durable. It is not in any sense a "vibrating diaphragm."