The numerous experiments which Reis made, and the many forms of instruments which he devised, prove his conviction of the importance of his invention to have been very deeply rooted. He had indeed penetrated to the very soul of the matter. He did not confine himself to one kind of tympanum, he tried many, now of bladder, now of collodion, now of isinglass, and now of thin metal. He varied the forms of his instruments in many ways, introducing the element of elasticity by springs and adjusting-screws. Though he chiefly employed one metal for his contact-pieces, he did not limit himself to that one, but left us to infer that the principle of variable contact was applicable to any good conductor, metallic or non-metallic. He knew better, indeed, than to limit himself in any such fashion; better, indeed, than some of the eminent persons who are now so willing to ignore his claims. Modern practice has taught us to improve the tympanum part of Reis’s invention, and to obviate the inconveniences to which a membrane is liable: in that part we have gone beyond Reis. But in the question of contact-points for opening and closing the circuit in correspondence with the vibrations, we are only beginning to find how much Reis was a-head of us. We have been thrown off the track--blinded perhaps--by the false trail of the “semi-conductor” fallacy, or by the arbitrary and unnatural twist that has been given by telegraphists to Reis’s expression, “opening and closing the circuit,” forgetting that he practically told us that this operation was to be proportional to, “in correspondence with,” the undulations of the tympanum. When we succeed in freeing ourselves from the dominance of these later ideas, we shall see how much we still have to learn from Philipp Reis, and how fully and completely he had grasped the problem of the Telephone. FOOTNOTES: [39] ‘Philosophical Magazine,’ April 1882. [40] ‘Atti del R. Istituto Veneto di Scienze,’ vol. vi. ser. 5. [41] Proc. Roy. Soc. No. 218, 1882. [42] See Proc. Roy. Dubl. Soc. Feb. 17, 1879. [43] Vide ‘The Electrician,’ Feb. 10, 1883. [44] Journal Soc. Telegr. Engin. and Electricians, vol. xii. p. 137. [45] Proc. Physical Soc. vol. ii. p. 259, 1878. [46] ‘Journal Soc. Telegraphic Engineers,’ vol. iv. p. 117, 1874.