( 359 ) 
of the above-named table have not the slightest value. ') Estimating 
the relation of the intensities of 2 sounds by hearing is rather 
precarious, but how it is possible to express the “clearness” in 
figures I cannot understand. 
In the following lines I wish to give a description of the manner 
in which I have endeavoured experimentally to investigate whether 
in reality an increase of the number of primary turns over and 
above the usual number does not strengthen or improve the telephonic 
sound. And if that does not take place, what may be the reason. 
To do so I made 10 different induction coils, described in Table I 
(page 360). The coils marked 4 are provided with an iron core, 
those marked B are not. For the rest, the coils bearing the same 
number are perfectly alike ; so for instance, the only difference between 
6A and 6B is that 64 has an iron core and 62 has none. When 
in future I speak of 2 coils, one of which has more primary layers 
than the other, I shall call the former for simplicity’s sake the coil 
of higher order. 
The microphone I used for these experiments was the “Hunnings- 
Cone”, a modification of the Hunnings-mierophone. ‘To measure 
the resistance of this microphone, twelve of them were put in one 
circuit and the resistance was determined. Then I tapped on all 
the microphones and the total resistance was again determined and 
this was repeatedly done. The mean of all these measurements, 
divided by 12, amounted to about 31/2 Ohm. 
From this microphone the ebonite mouthpiece was screwed off 
and a resonator, Fa; = 682.6 s.v., placed before the opening in 
such a manner that the narrower opening of the resonator was as 
close as possible to the vibrating plate of the microphone. Before 
the wider opening of the resonator an electro-magnetic tuning-fork 
Fa, was placed, kept in motion by a small accumulator. Resonator 
and tuning-fork were both made by Kornic. With my first 
experiments the resonator was fastened in a cork ring, fitting in 
the aperture of the microphone. It was then however evident that 
the microphone vibrated very irregularly, as regards the intensity. 
Then the cork ring was removed and the resonator, clasped in a 
separate stand, was placed before the microphone, so that resonator 
and microphone-box could not touch each other; I then found that 
1) L asked Mr. Preece to inform me where the original description of these experi- 
ments was to be found, whereupon he answered me that he was sorry to say he did 
not remember whence he had the figures, 
24* 
