170 THE ADDRESSES, LECTURES, ETC., OF 



vibrations of the diaphragm imparted by the voice to be accurately 

 represented in strength and duration by electrical currents, thus 

 producing the marvellous results of setting up analogous vibrations 

 in the diaphragm of the receiving instrument, which, though 

 weaker than the vibrations imparted to the transmitting dia- 

 phragm, so closely resemble them as to repeat the quality of voice 

 which causes the original vibrations. 



The currents transmitted are so minute as to escape observation 

 by the most delicate galvanometer, as the magnetic needle, how- 

 ever light, must be too sluggish to be moved visibly by such 

 quick impulses, and it requires an electro-dynamometer of ex- 

 ceeding sensitiveness to bring them into evidence. The rapidity 

 with which these reversing currents follow each other can be 

 accurately determined in transmitting the sound of a high-pitched 

 tuning-fork, and Mr. Kontgen concludes from experiments he has 

 made in this direction that not less than 24,000 currents can be 

 transmitted in one second. We here detect a rapidity of electrical 

 transmission far exceeding our most sanguine expectations in 

 endeavouring to increase the rate of transmission of telegraph 

 instruments by mechanical means, thus opening out a new field for 

 the inventive faculties of the Telegraph Engineer. 



The telephone is no doubt capable of great improvement, which 

 should chiefly be directed towards increasing the relative amount 

 of vibration of the receiving diaphragm. 



Improvements will, doubtless be directed also towards the ac- 

 complishment of simple methods of recording the audible messages 

 received, which has already been attempted by Mr. Edison, and of 

 carrying out such accessory objects as the ringing of call-bells and 

 the transmission of the sound-waves through additional circuits. 



Considering the minuteness of the electrical impulses and their 

 high electro-motive force, it seems probable that they will be 

 capable of being transmitted to very great distances through con- 

 ductors of comparatively small dimensions, provided only that 

 those conductors are not subjected to the disturbing influence by 

 induction of currents flowing through adjoining wires. It is well 

 known that owing to these disturbing currents the telephone can- 

 not be worked through a wire suspended with other wires upon 

 posts in the ordinary way, and it will be necessary to devise other 

 means of carrying the telephone conductor. 



