MAWSON & SWAN, 



41 



Magnetic Call Bells, dispensing with the use of a battery, 



for use with the Telephone, the pair... ... ... 6 



Microphone, with 2 cell battery ... ... ... ... o 



Do. lever form ... ... ... ... ... o 



on ebonite ... o 



lever form, with fly box ... ... o 



with sound box ... ... ... o 



Do. 



Do. 

 Do. 



Do. with 2 cell battery and Telephonic receiver 300 

 Cooke's Telephone Alarum o 8 6 



MATERIALS FOR TELEPHONIC EXPERIMENTS. 



/ s. d. 



Bar Magnets, 4 x -|, per pair 



Do. with adjusting screws 

 Diaphragms... 



Binding Screws, per doz. ... 

 Bobbins, empty, per pair ... 



Do. wound with No. 36 wire ... 



o 2 

 o 



O 

 O 



o 



and 15, Mosley-street> Newcastle-on-Tyne. 



3 



O 2 



3 



o 6 



3 o 



