connected with the Telephone. 285 



tried, but all with vexatious, disappointing, and dispiriting 

 failure. 



One of the earliest efforts was made by Mr. Willmot, who 

 hoped by increasing the number of diaphragms, coils, and 

 magnets acted upon simultaneously, and joining up all those 

 coils in series, to obtain a resultant effect that would magnify 

 the out-going currents; but the result showed that, while the 

 apparatus acted all right, the effect of displacement of each 

 diaphragm decreased with their number, and the ultimate 

 effect was the same as with one diaphragm. Mr. Willmot's 

 instrument, which was made early in October last, is on the 

 table ; M. Trouve, in Paris, seems to have been working on 

 the same idea. 



Increasing or varying the size, form, and strength of the 

 magnet has produced little or no apparent improvement; for 

 the resultant effect in all cases remained apparently the same. 



The greatest effect is produced with a compound horseshoe 

 magnet, which is indeed one of the earliest forms brought out 

 by Mr. Bell. Here we have two coils, utilizing the maximum 

 number of lines of force ; and the effects produced are certainly 

 the finest I have yet experienced. At Southampton, on the 

 14th inst., in a small office, Mr. Willmot's voice (he was in 

 London) was heard distinctly by the seven or eight persons 

 who were in the room at the time. Though I have made one 

 with the largest and most powerful magnet I could obtain, the 

 result has been as disappointing as in the previous cases. The 

 telephone has certainly been brought to this country by Mr. 

 Bell in almost its perfect theoretical form ; he is still labouring 

 to improve it; and I am sure we all wish him success. 



V. Applications. 



However small and howeA^er sudden the currents may be, 

 the telephone records them with great accuracy ; no known 

 form of galvanometer or galvanoscope will do so. 



It is admirably adapted for showing the currents of induc- 

 tion set up in contiguous coils or contiguous spirals. If re- 

 versals or intermittent currents be sent through one spiral 

 while the other be gradually removed away, the rapidly dimi- 

 nishing effect of increased distance is very evident ; indeed 

 all the phenomena of magneto-electric induction are strikingly 

 shown by its means. It is also admirably adapted as a detector 

 in the bridge of a Wheatstone's balance to test short lengths of 

 wire, and it will probably enable us to obtain a closer approxi- 

 mation to equality than we have yet secured ; it also enables 

 us to adjust condensers with great accuracy. 



M. Niaudet, of Paris, has shown how it can be utilized to 



