electric machines and the means of increasing the E.M.F. were discussed,
the conclusions pointing to the future use of very large machines and
very high velocities. The future of telephonic communication received a
passing remark, and attention called to the future of electric railways.
The small experiments of Siemens have determined the ultimate success of
this kind of railway. Their introduction is merely a question of time
and capital. The first cost of electric railways would be smaller than
that of steam railways; the working expenses would also be reduced.
The rails would be lighter, the rolling stock lighter, the bridges and
viaducts less costly, and in the underground railways the atmosphere
would not be vitiated.

"About two years ago, it struck Professor Ayrton and myself, when
thinking how very faint musical sounds are heard distinctly from the
telephone, in spite of loud noises in the neighborhood, that there
was an application of this principle of recurrent effects of far more
practical importance than any other, namely, in the use of musical notes
for coast warnings in thick weather. You will say that fog bells and
horns are an old story, and that they have not been particularly
successful, since in some states of the weather they are audible, in
others not.

"Now, it seems to be forgotten by everybody that there is a medium of
communicating with a distant ship, namely, the water, which is not at
all influenced by changes in the weather. At some twenty or thirty feet
below the surface there is exceedingly little disturbance of the water,
although there may be large waves at the surface. Suppose a large
water-siren like this--experiment shown--is working at as great a depth
as is available, off a dangerous coast, the sound it gives out is
transmitted so as to be heard at exceedingly great distances by an ear