197 



Vcariety in toneseleetion. My expeiience has been represented graphic- 

 ally lower down. 



It appeared to nie, that lor this selection the telephone proved to 

 be of greater use than the microphone. This prevalence is determined 



O, aj, I, Ci w, dt d.i, e^ i 6, ^, ^,«, o^ a^* h it «i <i '^4 <« 



fiaige teleplionc-piate. 



U_ix 



e, OA i, Ct cSi d^ dj^ (i C Sh ii 9'', «i «W. *i 'a (.h "4 d^. 



Middle-sized teleplione- 

 pUite, UiiL'knessO.ll m.m. 



'^1 ' ' I ■ ' ' ■ I I ' ' ' M I I I I 



Tclephoneplate of 

 0.16 mm. thickness 



1 



_L 



a, a,s, h fi cs. dj. ds.. c, /^ 4 <7j ^.^, "i "^^i ^^ <ö <;^i '^j "^'^j *j 'j '!^j ^j 



J__L 



■ ■ ' 



Tliickness of' plate 

 0,24 in m. 



Four special combinations of microphone and telephone of different tone-selection. 

 (Max. amplitude for each apparatus called lOOj. 



