558 MR JAMES BLYTH ON THE TELEPHONE AND MICROPHONE. 
The next experiment which I have to mention was suggested by a descrip- 
tion of the microphone lately invented by Professor Hucues. Instead of the 
pointed piece of retort carbon supported between pieces of the same material, 
as used by him, it struck me that gas-coke or cinders were likely to answer the 
purpose tolerably well. To test this I included in the circuit of an ordinary tele- 
phone a single Leclanché cell and a jelly jar half filled with cinders broken into 
coarse fragments. The connections were made by slipping down at opposite 
sides, between the cinders and the sides of the jar, two strips of tin to which 
the circuit wires were attached. When this was used as a transmitter articulate 
sounds were heard very loud and distinct in the distant telephone, though 
occasionally marred by what appeared to be the rattling of the cinders in the 
jar. With this transmitter the words were also quite audible, even when the 
speaker stood several yards away from it. I next took a shallow box made of 
thin wood about 15 in. by 9 in., and filled it with cinders, taking care in the 
first place to nail to the inside of its ends two pieces of tin to which wires 
could be attached. Having nailed down the thin lid of the box, and 
included it in the circuit of the telephone along with one Leclanché cell, I 
found that it made both a very sensitive microphone and also a most excellent 
transmitter for the ordinary telephone. ‘With three of these boxes hung up 
like pictures on the walls of a moderately sized room, and connected in circuit, 
almost any kind of noise made in any part of the room was distinctly revealed 
in the telephone. Speaking was distinctly heard, and a part-song sung by 
two voices in the middle of the floor was rendered with surprising clearness 
and accuracy. 
In my next experiment, {still usmg the same cell in the circuit, I tried as 
transmitter a single elongated cinder with the wires wound tightly round each 
end. Sounds uttered close to this cinder were quite audible in the telephone, 
but I failed to hear them when there was substituted for the cinder a carbon 
from a Bunsen battery with brass clamps at each end, into which the circuit 
wires were tightly screwed. Possibly, either the more porous and friable nature 
of the cinder, or the comparative looseness of the wire connections with the 
cinder may have had something to do with this difference of effect. 
I next removed the Leclanché cell entirely from the circuit, and used as 
transmitter a jelly jar containing dry cinders. With this I sometimes fancied 
that I heard sounds, but they became distinctly, though faintly, audible as the 
cinders became somewhat moistened by the breath of the speaker. I then 
poured water into the jar so as almost to cover the cinders, and then the 
sounds in the telephone were almost as distinct as when the Leclanché cell 
was in the circuit. I did not, however, hear any sound with the cinders 
removed and water only in the jar, not even when the resistance of the water 
was diminished by being slightly acidulated. 

