474 



SCIENCE. 



[Vol. II., No. 85. 



screw is arranged in a similar manner, so as to 

 regulate the distance of the contact-piece from 

 the end of the lever most remote from the 

 membrane. In all these instruments the screw 

 acting upon the spring is expressly contrived 

 to facilitate such an adjustment as will insure 



the breaking of contact under the impact of 

 the sound-waves. Its function is related to the 

 tension and elasticity of the membrane, to 

 make a pressure so light in any case, that the 

 vibrations should be able, without fail, to sepa- 

 rate the contact-pieces. 



To saj^, as Professor Thompson repeatedly 

 does, that Reis emplo3'ed his mechanism with 

 the express intention of producing a variable 

 current bj* the change of contact-resistance, and 

 that he consciouslj' and purposelj' utilized this 

 principle, — at that time hardly recognized anj-- 

 where, and of which the practical application 

 was not discovered till several years later, — is 

 a gross misrepresentation, and an utter perver- 

 sion of the facts. Eeis did not know, and 

 could not know, that the strength of a current 

 could be controlled bj' the varying pressure 

 of the couducting-surfaces between which it 

 passes. Nowhere in his writings, — -whether in 

 his description of the instruments, or in the pro- 

 spectus issued with them, or in his letter to 

 Mr. Ladd, — nor in the article of Professor 

 Bottger and the report of Von Legat, is there 

 the remotest suggestion that the transmitter 

 acted, or was intended to act, otherwise than hy 

 breaking the circuit. Nor is anj' thing of the 

 kind to be found in any of the publications of 

 the day, relating to this matter. With the 

 knowledge which we now possess, of the vary- 

 ing resistance of pressure-contacts, it is indeed 

 easy, by a slight modification, to cause the 

 contact-pieces to vary the current by change of 

 pressure, and thus reproduce the vibration-form 

 with approximate accuracj'. But to do this, it 

 is necessary to prevent them from separating so 

 as to break contact and interrupt the current. 

 Such a modification, however slight it maj' be, 



totally changes the function of the contact- 

 pieces, and amounts to a radical transformatiori 

 of the apparatus. It is the verj- thing Reis- 

 studiousl3' sought to prevent. 



That Eeis speaks of the foi-m of acoustical 

 vibrations, and their graphical representation 

 by a curve, is no proof that he supposed his 

 transmitter to act otherwise than by break- 

 ing the circuit. Yet Professor Thompson 

 says (p. 165), " It is certain that Reis did 

 not in any of his writings explieitlj' name 

 an undulatory current : but it is equall}^ 

 certain that, whether he mentioned it or 

 not, he both used one and intended to use 

 one." Eeis nowhere claims that his appa- 

 ratus realized the normal vibration-form, 

 even in the case of a simple tone ; and 

 there is no evidence in all his writings ta 

 show that he had ever considered the mo- 

 tions at the receiver to be the same as those 

 of the original sound, except so far as there 

 was a correspondence in period or rate of these 

 motions with those at the transmitter. The 

 idea of causing the motions in the receiver to 

 have the same vibration-form as those in the 

 transmitter originated with Bell, as did the 

 method of securing this correspondence, which 

 is indispensable to the reproduction of spoken 

 words, by the use of an undulatory current. 

 Says Sir William Thomson ( Tel. journ. and 

 electr. rev., v. 293), "Mr. Graham Bell con- 

 ceived the idea — the wholly novel and origi- 

 nal idea — of giving continuity to the shocks, 

 and of producing currents which would be \n 

 simple proportion to the motion of the air pro- 



duced by the voice, and of reproducing that 

 effect at the remote end of a telegraphic wire." 

 The author of this book will scarcely have the 

 hardihood to assert that his illustrious country- 

 man, one of the greatest masters in electrical 

 science, uttered these words in ignorance of a 

 thing so well known as Reis's telephone. 



