The times dispatch. [volume] (Richmond, Va.) 1903-1914, 1907-01-27

that could reach the diaphragm would
cause such a tumble of sound that the
words of a telephone message could not
be understood.
SO the problem before the engineers
has been to find a way to prevent the
telephone current from "decaying' dur
ing the journey of n message over the
lines. That is, the engineers have sought
means to counteract the inevitable loss
of efficiency in the current and to keep it
as near as possible at it's original
strength. Two methods of doing this
have been tried. Separately they have
worked out we'll; but as yet they have
not been applied commercially to the
same line.
The two devices that promise so much
for the extension of the range of long
distance talking are the loading coil and
the repeater. Though the ends they
accomplish arc, to a certain extent, the
same. the principles on which they work
are entirely different. When the cleo
trical current from the transmitter of
one telephone starts out on its journey
to the receiver of another telephone a
thousand miles away, say, it loses
strength very fast. sinking away by de-
grees until finally it becomes too weak
TO reproduce vibrations distinctly The
loading coil which was invented by Pro-
lessor Michael ]. Pnpin, of Columbia
University, acts as a sort Of stimulant
1T consists of an iron core upon which
Is winding upon winding, of fine wire
which the talking current is passed In
such a way that 1T is strengthened
against the decaying processes, and main
tanned at level high enough to give
satisfactory transmission. These coils
are attached to a line two, four or may
be eight miles apart, and their use APP
proximately doubles the range OF the
telephone.
The repeater, which is a later inven-
ton, produced by one of the Bell en-
gneers, operates Very differently. AS
its name signifies, it actually repeats the
message, which, coming through u re-
ceiver, reproduces- itself automatically
on a transmitter. This allows of putting
/, new current into the line, just as the
| original current is introduced at the
! transmitter of the subscribar's telephone
/ The result is practically, to start the
| message all over again with a fresh lease
! OF life, though naturally the force that
!, carries it cannot be made quite as goot
! as new. A repeater in the middle of {
I long distance circuit extends the range
| of talking about fifty per cent.
4 While these remarkable; strides in adj
\ vance have been made there have beer
other influences at work which tend tc
! delay rather than hasten the extension
i
transmission would be obtained over
4 lines of heavy copper wire strung upor
! poles. In practice, however, the Ions
distance lines must run in and out OF
switchboards along the way, and her,
4 and there the messages must leave thu
! poles to travel forp soma distance 9undcl
| ground. The loss of efficiency lin Wha
4 are called the substation loops-that Il
to say, the lines between the centra
Offices and the siibscrlbers' telephones
reduces the distance OF possible 1nns
i mission full third, This Is because q
I the resistance offered to the passage o
4 the current By apparatus and by th'
small wires that have to be used II
4 underground cables and in the wirint
\ of buildings, and SO on. When n tele
! phone message passes through n switch
I Ing station eitaers, IL aregulai. central
office orone nj the long distance stations
ilipcated outside of large cities, the effe6
/ on the current may be as great. under
some conditions, as would lie produced
4 Us. adding l5g miles OF line.