first one and the last three, and he several times emphasized the statement, that the final undulations of the last stage were to be similar to the original undulations of the first stage. The air at the listening end, the armature of the receiver, and the magnetism of the magnet, were all to be set by the fluctuations of the current into undulations corresponding with those of the tympanum at the speaker’s end, and of the waves of his voice. It is perfectly clear therefore, that he regarded as self-evident the intermediate stage, and he did not dwell upon the necessity of the point, that his transmitting-current must also vibrate, because this was obviously so, and was only an intermediate matter of secondary moment. He chose rather to point out the necessity of unification between the first and last stages, leaving it to common sense to see that the “interruption” or the “opening and closing” of the circuit must be effected in a manner corresponding to the undulations of the impressed sound-wave. Had the “interruptions” not been of the nature of corresponding variations of contact, the current could not have been set into corresponding vibrations, and the armature of the electromagnet could not have reproduced the vibrations of the transmitter. Clearly Reis’s whole conception of telephony included as a minor and intermediate step the fact that the current was, by the action of the transmitter, caused to vary in strength in correspondence with the undulations of the tympanum--that, in fact, it was made to undulate by the action of the tympanum and of the interruptor which opened and closed the circuit in obedience to the undulations of the tympanum and in proportion to them.