558 
Proceedings of the Boyal Society 
room where the other is placed, and there is no doubt that the sound 
seems to come from the magnet itself. The same is done in the case 
of a compound Telephone with 25 bar magnets to one iron plate 
exhibited by the author, 
In conclusion, the author considers that the theory now explained 
must be taken to supplement that of Mr Graham Bell (1), because 
the phenomena alluded to undoubtedly take place, and (2), because 
it is the only theory which explains the action when the vibrating 
plate is not made of iron, or when there is no vibrating plate at all. 
5. Some Experiments with the Telephone. 
By John G. M‘Kendrick, M.D. 
During the past two months my attention has been directed to 
the telephone, chiefly as an instrument which illustrates in a 
remarkable way the delicacy of hearing. As some of these experi- 
ments are novel, and may possibly assist those who are investigating 
the physical phenomena of the instrument, I beg to give a short 
account of them to the Society. To save circumlocution in descrip- 
tion, the term “ proximal ” will be applied to the telephone 
receiving the stimulus, and the term “ distal ” to the one at the 
other end of the arrangement. Thus, if A talks to B, A will use 
the proximal, and B the distal telephone. 
1 . Transmission of the Sounds o f Tuning-Forks. — At an early stage 
of my investigations, finding it convenient to have a constant 
source of sound at the proximal telephone, I placed a telephone 
opposite one of the limbs of a tuning-fork, kept in vibration by an 
electro-magnet, the current being interrupted automatically by the 
fork itself. At the distal telephone the sound could be distinctly 
heard. Then I removed the disk from the proximal telephone, 
and allowed the limb of the fork to play in front of the naked end 
of the core. The distal telephone then sounded more distinctly 
than before. The next step was to remove the metal disk from the 
distal telephone, and apply disks made of vulcanite, porcelain, 
glass, paper, wood, a large piece of iron 1 J inches thick, a thick rod 
of iron, 8 inches in length by 1 inch in diameter. Still the sound 
of the proximal telephone could be heard, though faintly. There 
could be no doubt of the fact. To ascertain whether the effect 
might not be due to the communication of mechanical vibrations 
