Philipp Reis: Inventor of the Telephone / A Biographical Sketch

by Silvanus P. Thompson

Fig. 43.

It is a fact that in Berliner’s instrument it is usual to make the contact-pieces, or one of them, of hard artificial coke-carbon, as this substance will neither fuse nor rust. But Berliner’s transmitter will transmit speech perfectly if the contact parts be of brass, silver, platinum, carbon, or almost any other good conductor. In most of Reis’s instruments the contact-pieces were usually of platinum; but they work quite as well if artificial coke-carbon is substituted. In fact, Reis’s principle of variable and elastic contact is applicable to contact-pieces of any material that is a good enough conductor of electricity and hard enough for the purpose. The main improvement in Berliner’s transmitter is the substitution of the metal tympanum for the membraneous one, which was liable to become flabby with moisture.

Fig. 44.

We pass on to Blake’s transmitter, which is the one more generally used in Great Britain than any other. The drawing, [Fig. 44], of this instrument is taken from the specifications of Blake’s British Patent, and shews all that concerns the contact-parts. It does not show the accessories, the induction-coil, or the form of adjusting screw and frame peculiar to this instrument. Inspection of the figure shows that this transmitter consists of a mouthpiece in the form of a conical hole bored through a stout plank of wood, and closed at the back by a metal tympanum of exactly the same size as that of Reis, behind which the interruptor is placed, precisely as in some of Reis’s instruments. In this interruptor both the contact-parts are supported on springs, resembling, even in the curve given to them, the springs Reis used. The first of the contact-pieces is a small metal spike. Concerning it Mr. Blake remarks (page 4 of Specification):—“It is desirable that it should be formed of, or plated with, some metal, like platinum or nickel, which is not easily corroded. It may be attached directly to the diaphragm, but I prefer to support it independently, as shewn, upon a light spring.” ... “This method of supporting the electrode ensures its contact with the other electrode under some circumstances when otherwise they would be liable to be separated and the circuit broken.” In fact this spring serves functions precisely identical with those of the springs used by Reis. The second of the contact-pieces may be described as a mass of metal at the end of a spring. Of it the patentee remarks:—“This weight may be of metal which may serve directly as the electrode, but I have obtained better results by applying to it, at the point of contact with the other electrode, a piece of gas-coke or a hard-pressed block of carbon.” As a matter of fact, a mass of silver or of nickel or of platinum will transmit talking perfectly, but these metals, though better conductors, are more liable to corrode and fuse, and may require therefore more frequent renewal, than gas-coke. Since, then, it is immaterial to the action of a Blake transmitter what substance is used for the contact-pieces, it is clear that the principle of employing an interruptor mounted on springs is the real feature of the instrument. Reis also mounted his interrupters with springs, and for the very same purpose. The function of the weight on the second spring of the Blake transmitter is to resist the movement of the tympanum, and to “modify by its inertia the variations of pressure” between the two contact-pieces. In other words, it acts partly as Berliner’s transmitter, by inertia. So did one of Reis’s instruments, as we have seen. In the Blake instrument there is the happy idea of applying both the spring-principle and the inertia-principle at once. Yet, in spite of this, if the speaker shouts too loudly into a Blake transmitter, he will cause abrupt breaks between the contact-pieces instead of producing partial interruptions in the contact, and in that case speech will, as heard at the other end of the line, be spoiled by a rattling noise. It is possible, also, with Reis’s instruments to spoil the articulation by shouting too loudly, and causing actual abrupt breaks in the continuity. If Blake’s interruptor can be worked as a make-and-break in this sense, so can Reis’s: for there is not one of the features which is essential to Blake’s instrument that cannot be found in Reis’s also.

By way of further carrying out the comparison between Reis’s methods of combining his tympanum with his contact-regulator, and the methods adopted by later inventors, we give, in [Fig. 45], ten comparative sketches, the first five of which illustrate Reis’s methods. In these sketches the only liberty taken is that of representing no more of the instruments than the actual parts wanted in the comparison. No. 1 represents the working-parts of Reis’s first model ear, with its curved lever, platinum-tipped spring, and adjusting screw. No. 2 shows the springs, screw, and contact-pieces of Reis’s bored-block transmitter (“fourth form:” compare Figs [9] and [10], p. 21). No. 3 shows the curved lever, the springs, and the adjusting screw of Reis’s eighth transmitter (“lever” form). No. 4 gives the working parts of Reis’s ninth transmitter, described in detail on p. 27. No. 5, in which the tympanum is placed in a vertical position, merely for convenience of comparison with the other figures, shows the working parts of Reis’s final form of instrument, in which gravity and the inertia of the upper contact-piece enabled him to dispense with the adjustment of spring and screw. No. 6 shows in profile Berliner’s transmitter, which may be instructively compared with No. 5. No. 7 shows the working part of Blake’s transmitter, which should be compared with Nos. 2 and 4: even the curve of the springs imitates that adopted by Reis. Nos. 8, 9, and 10 are forms of transmitter devised by Edison. No. 8 is copied from [Fig. 10] of the specification of Edison’s British Patent. It will be seen that here there is an interruptor placed on each side of the tympanum, and that each interruptor consists of a short spike mounted on a spring and furnished with an adjusting-screw. “Platina foil disks,” says the inventor, are to be secured to each side of the diaphragm, and against these disks, as in Reis’s instruments, press the contact-points of the interruptors. The patentee also states (p. 7 of his Specification), that for these contact-points “any substance not liable to rapid decomposition” may be used. This term includes all the substances used by Reis, and a great many others. It will therefore be seen that this whole device is nothing more than a Reis transmitter with the contact parts duplicated. Yet this instrument was intended by Edison to transmit speech, and will, like Reis’s instrument, transmit speech if properly used. No. 9 of the set of sketches is taken from [Fig. 25] of Edison’s British Specification, but omits the induction-coil and other accessories, retaining the parts wanted for comparison. The patentee thus describes the parts figured. “The tension-regulator [meaning thereby the interruptor or contact-regulator] is made of platina-foil upon the surface of two soft rubber tubes; one on the diaphragm, the other on the adjusting-screw.” It is interesting to note here how the ingenuity of the later inventor led him to vary the construction adopted by the original inventor in substituting an elastic cushion of soft rubber for the springs of the older instruments. But the principle of combining a tympanum with a contact-regulator, which was Reis’s fundamental notion, is here also the leading idea; and the further idea of obviating abrupt breaks in the current by applying elastic supports is also carried out. Edison even copies Reis in having an adjusting-screw, and he applies the very same substance—platinum foil—which Reis used in his very first and his very last transmitter. Edison’s transmitter transmits speech very fairly, even without any of such later accessories as induction-coils; and why should it not? It is constructed on the very lines, nay, with details almost identical with those prescribed by Reis in describing his invention. It embodies those fundamental ideas which Reis set before him when he said, “Taking my stand upon the preceding principles, I have succeeded.”