THE TELEPHONE AND ITS IN VENT OB. 549 



telephone for an hour at a time, the distance of the stations from each 

 other heing about one hundred and fifty feet. He says : " I remem- 

 ber especially that Mr. Reis speaking through his instrument I dis- 

 tinctly heard the words, 'Guten Morgen, Ilerr Fischer' ; 'Ich komme 

 gleich ' ; ' Passe auf ' ; ' Wie viel Uhr ist es ? ' ' Wie heisst du ? ' " 

 Heinrich Hold, a colleague of Reis in the same institute, gives de- 

 tailed testimony of talking successfully through the telephone. Hein- 

 rich F. Peter, the musical teacher, then and still at Garnier's Institute, 

 says, "Philipp Schmidt read long sentences from Spiess's 'Turnbuch,' 

 which sentences Philipp Reis, who was listening, understood perfectly, 

 and repeated to us." Being incredulous, and to further test it, Herr 

 Peter spoke some impromptu nonsensical sentences through the tele- 

 phone, such as "Die Sonne ist von Kupfer," which Reis understood 

 as " Die Sonne ist von Zucker." 



Mr. S. M. Yeates, instrument-maker of Dublin, writes that in 1865 

 he exhibited Reis's telephone to the Dublin Philosophical Society, 

 substituting an improved electro-magnetic receiver for the knitting- 

 needle receiver (shown in Fig. 2), the transmitter being the same as in 

 that figure. Yeates's receiver was an electro-magnet with a vibrating 

 armature, mounted on a spring attached to a sounding-box. William 

 Frazer, M. D., member of the Council of the Royal Irish Academy, 

 writes, March 13, 1883, that he was present on this occasion, that 

 various questions were asked and answered, and that "the separate 

 words were most distinct, the singing less so." The individual who 

 spoke was easily recognized by his voice. (It has been stated else- 

 where that Yeates improved the Reis transmitter by placing a drop 

 of water between the platinum surfaces of loose contact.) 



In an appendix, which is not really separable from nor less impor- 

 tant than the rest of the work, Professor Thompson discusses the rela- 

 tion of Reis's instruments to those now in use, and also Reis's devel- 

 opment and use of the variable or "undulatory" electric current, 

 corresponding to the undulatory curves of sound-pressure, which he 

 graphically represents, and to which he often refers. 



In the first section, Professor Thompson points out that Reis's 

 transmitters preserve throughout, first, the tympanum to collect the 

 voice-waves, and, second, two or more electric elements in loose or 

 imperfect contact with each other, so combined with the tympanum 

 that the motions of the latter correspondingly alter the current of 

 electricity flowing between the contact-pieces. Reis's apparatus is 

 not, therefore, an " interruptor," but a " current-regulator." The con- 

 tact-pieces, one or both, were mounted with adjustable springs, or held 

 together by gravity, so as to vary the current without completely 

 breaking contact, in the same way, and for the same purpose, as in 

 the Berliner, Blake, and other modern transmitters. Disregarding 

 induction-coils and other accessories, the fundamental principle of 

 these later instruments is the combination of a tympanum with a cur- 



