42 A. G. Bell—An Induction Balance 
Exp. 5. The same coils EK F, used in Exps. 2, 3 and 4, were 
tried once more with a battery of six large bichromate ele- 
ments, and with a condenser, G, in the primary circuit as 
shown in fig. 17. 
Result: Hearing distance 138, or more than 5 inches. 
This great increase in hearing distance seemed to be chiefly 
due to the condenser, for upon disconnecting it the hearing dis- 
tance was little more than ge", but further experiments prove 
that other causes also contributed to the result. 
Exp. 6. When the condenser was in circuit and the leaden 
bullet close to the coils (arranged as in fig. 17) the sound pro- 
duced by the telephone was a musical note whose pitch was 
the same as that normally produced by the vibration of the. 
reed of the interrupter. ingled with this tone could be dis- 
tinguished a number of feebler tones of very much{ higher 
pitch. Upon withdrawing the bullet gradually from the coils 
the fundamental sound became fainter, and one of the hig 
upper-partial tones gradually acquired prominence; and ata 
distance of about 8 or 9™ the fundamental could no ‘longer be 
distinguished, but the high tone persisted, and was clearly 
audible up to a distance of 18™. The effect was very striking, 
and when the bullet was moved to and fro parallel to the plane 
of the coils EF at a distance of about 10™, the telephone 
emitted a role tieslings sound each time the sensitive area 
(H) was pass 
It was noticed that other metals, such as iron, brass and 
copper, did not seem to reinforce this high tone to any great 
extent, but brought out the fundamental at every distance 
where an effect was produced. 
Exp. 7. The condenser G (fig. L7) was removed from the 
circuit and the leaden bullet held about 4 or 5™ from the coils 
KF. The fundamental tone was heard, and the characteristic 
upper. partial Aga also be distinguished, but it was onl 
faintly audibl Jpon now suddenly replacing the condenser 
the high Sabie paral tone was instantly reinforced as if by a 
or 
p. 8. The rheotome employed to interrupt the primary 
nak (which had been placed in a distant room) was found to 
be vibrating badly. The reed I of the instrament (see also 
