, 1877-05-16

DTdln through TIE AUDITORY nerve. MS Cell"
cate apparatus is capable of distinguishing or
rather Analysing composite sounds, musical
tones, noises, e. The wave length being
a physical fact independent Of the ear, but
dependent on the number Of impulses or vi5ra-
tiOnS caused in the medium of transmission,
the greater the number Of these The higher
will be the pitch Of the tone transmitted to the
ear, and the slower The vibrations the lower or
gr&yef will be tire tone,
When c string is stretched and vibra.ed BY
striking or pulling the vibrations produced in
it are dependent on its azure, tension, and
thickness, and thes5 vibrations give rise to q
musical note if their number per second is
sufficient 20 produce that effect. The range
Of vibration per second for musical sounds
Is between 40 and 10000; that Is If the
number falls below ~ per second the sound
or ncte Is 50 grave as to become q noise OF a
series Of noises or beats. If the number
exceeds 10000 the ear cannot appreciate the
nO:e, which is Of the highest pitch. The
actual range in music rarely passes above
5000 vibrations per second, but sometimes
in organ pipes falls below forty.
AS electricity is the potent agent employed
In the operation Of the sound telegraph, or
telephone, it is also necessary to understand
something Of Its nature when studying that
4OtA4H AAOlO 11oti AiACuks VI IL SGhE v sun
plici'y OF description and TO convey an intelli-
gible idea Of the mobility and sensiliveness Of
the subtle force, it is usually called a fluid,
although 1t is not such in the strict meaning
q the term. Il lows, however, along conduct.
Ing media as fluids follow channels, but is I'M.
Influenced by the force of gravitQtion. Per
haps this property will De better understood
when 1t is stated that electricity always seeks
to escape from its condition as a force TO one
Of l%atenoy in nature, which is its normal condi.
ton, Electricity perVades everything-the
earth, the air, the water, and all things thereon
and thsreia. Matter is, therefore, a natural
reservoir of electricity, whence it can be drawn
by a process Of development, and employed for
various purposes while it is returning TO lis
original condition. 70 make a simple c0mpa.
rison in this regard it is only Necessary to
pUint cut the process by which water is made
to serve as a mechanical motor when raised 10
q high level for that purpose. The raising Of
the water is an expenditure OF power which pro,
duces no effect OH the work proposed to be per-
formed, but it gives the water q power which
is known in mechanics as the energy of posi-
tion-that is, its position when raised represents
a force that may be employed for the purpose
to be served. Jus. in the same way the
development Of electricity from its condition of
ldteuOy tH(O II u uJ hdHilO OlG INV 10 u
from q passive to an active and employable
force, and gives it an energy Of condition
which can ba used in its liberation as in
descending water. There are various
ways of developing electricity. Heat, fric-
ton, and chemical decomposition are, however,
the most frequently employed, and represent
the chiefmodeS Of development.
AS soon as electricity is developed on a body
suited for the purpose, say a glass rod, its. sur
face becomes covered with the electric Huid,
the positive occupying one end and the negative
the other. The middle Of the rod becomes a
neutral line between the two fluids. But not
only do the positive and negative electricity
take opposite ends, being, as stated, mutually
repellant they also seek the extremities and
accumulate there in greater quantities than near
or the neutral line. This is caused. c~uriously
enough, by two distinct and directly opposite
kinds of effort-namely, that which separates
the fluids and that by which they seek to re-
unite.
Now, If conductors or electrodes, as they are
scientif cally termed, are attached to the ends
of the charged rod or battery. the ends of these
wires will become. in turn charged with cleo.
tricity of opposite. kinds but if these ends are
brought together so as to touch, the positive
fluid Of the one unites at once with the mega
tive fluid of the other. both accomplishing into
their original condition of latent electricity
again and Inseparabls. unlsass 1.-the process at
tDa