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.” [Illustration: Fig. 45.]