New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1894-06-03
SPEED IN OCEAN CABLING
PLANNING TO INCREASE 1T.


Soon after submarine telegraphy became a practi.
cal success 1t discovered that the wire used for
that purpose would not work as we'll as q land
wire. With the best transatlantic cables only from
twenty-five to thirty words minute can be trans
mtted ntelligbly; land lines the only limit IL
the skill OF the operator the speed OF an auto
matte machine for transmitting. which latter often
reaches 200 or 300 words minute The difficulty In
cabling, long considered insurmountable, Is due 10
the fact that ocean wire has an Insulating coat
OF gutta-percha and this develops on its outer sur
face certain amount Of negative electricity by In
duction every time that positive electricity Is sent
into the wire. The phenomenon Is the same as that
witnessed on the outside Of a Ieyden Jar when the
inner coating is charged 1t may also be observed
in an instrument called the condenser. Therein q
number OF metal plates are separated from each
other by insulating material. and alternate ones
are connected among themselves, and With COM
mon wire Fin up set OF plates from the posi-
tive pole OF a battery or dynamo and in the other
equal amount of negative electricity VIII De
excited. The copper core Of a cable them Is nos
only conductor, but IN combination with Its coat
ing It Is also a OF reservoir or sponge. Hence.
before any Of the current put into II at one end
out at the other. certain amount OK
electric energy must be consumed in the inductive
process. OF this is done very quickly but IL
requires appreciabe length OF time and wastes
Just so much current. and the longer the cable tho
greater the loss OF time and current Length In.
den Jar. Unless the opening and closing OF the cir
cult by the sender are done slowly enough. there
fore. either signals at all will be observed by the
receiving opera tor else they will be faint and in
dstinguisheble.
Now II there could be devised way to reduce the
"electrostatic capacity" OF the cable less current
would lie absorbed and more would be delivered for
effective at the end Of the line Dr. NJ ]. Pupin.
OF Columbia College whose original Investigations
OF electrical phenomena for the last two or three
years have attracted wide attention. now proposes
such method lie would introduce into the line,
at frequent and regular intervals these very in
struments TO which reference has just been made.
namely condensers The current sent into the first
OF these sections would not pass into the second.
since the two sets Of plates in the condenser would
be insulated from each other. But secondary
current would be Induced in the interposed instru-
ment, and this would traverse the next section.
Thus each portion OF the line would act upon the
one beyond Il. that electric action would still be
manifest nj the terminus as II there were con-
tinuous conductor one result Of this arrangement
would be that the e.ectrostac capacity OF the cable
as a whole would be limited to that OF any one OF
those sections, AMI hence reduced TO almost moth
ing: and that energy absorbing phenomenon Of
Zine" Induction would be avoided The signalling
service would be performed through the inductive
action OF the condensers proper and these would
purposely have ample capacity, greatly exceeding
that OF the wire sections.
At each junction in the line short side-track or
would
duction coil OF enough resistance TO refuse 10 take
the main current so long as the condenser In
working order. But n the latter should break down.
no other route would be Open and the current
would then flow through the coil into the next Sec
ton.
In long-dstance overland telephony, as well as IN
submarine telegraphy. trouble is now experienced
from induction; and this puts limit on the length
of line that can be successfully operated At
present human speech is not now transmitted more
than about 100 miles. DIR. Pupln, however. be-
leves that his invention removes that obstacle
and that IL opens the way also to
lephony BY simple adjustment OF apparatus he
thinks the same wire may be used for both tele-
phones and telegraphs The cost of the appliances
here mentioned introduces commercial factor OF
such Importance that the practical application Of
this idea to submarine wires may be deferred for
a long time, perhaps. even though II be feasible
electrically; but technical publications of high
standing regard with favor the suggestion OF try
ing Il In telephone service Here, again. the ques-
ton OF expense will come in. Scientifically, how
ever the principle Is admitted 10 be sound by SO
eminent an authority Herbert Laws Webb, gen.
eral manager of the Metropolitan Te.epnone ana
Telegraph Company.
An essential feature OF this system Is the "tun-
ing OF the sections composing the line. In some
striking and beautiful experiments which The
Tribune described last January. DR.. Pupln
employed a circuit into which he had introduced
a condenser and a self-induction coil. He then
showed that such a circuit had a natural
period" Of It's own; that is. II would moro
easily transmit an alternating current OF particu-
lar frequency than one Of any other frequency.
IT, though he modified the capacity of his conden-
ser or the effect OF his induction coil, the period
could be changed. Just the tone OF piano or
violin string could be varied by altering the ten
sion. This, then. Is what he means by tuning
an electric circuit, and by carefully calculating the
capacity Of the condensers inserted in an ocean
cable the sections could be easily tuned desired
Such adjustment would be necessary for either
ocean telegraphy or overland telephony alone; ana
II cable were to be used for botn ,elegraphc and
which four small condensers introduced for
tuning 1t. would also be required al the starting
point ,.. .. ,,ho, ~ s.s III.
originator OF this system would not be me arse,
cylinders rolls OF rbbon-ike plates, wound apout
the twenty h vi he baad Would
says. give the required capacity. They need not
h hays eS Gross These ought to be-
intervals OF several miles, for Atlantic service ana
sruetea f for n ony t Twice the cost Of those
use on a longer line say across the Pacific II
lspSer humber Of groups OF ribbon eondensers
has been said at the beginning OF TINS article tnas
words a minute may be transmitted over land llnes
by sesraphy On short d srf frans STi Goo Words
minute. says Kurke one OF the wsstern
necessary to reduce the speed. To Chicago 200
words A minute is an average rate from New-York;
10 81 Louis lis to Boston perhaps 300 words might
be sent. But DR.. Pupln thinks that MS system
would make Il possible, both by land and sea, 10
transmit 500 or COO words minute As yet. how
ever no actual test has been made on long ocean
cables. , ,,, At,
DR.. Pupin has also had in view. In deysing this
such buoys whenever tried. have been supplied
with an alternating current through a cable re-
semblinR that employed for elegraphing across the
Atlantic and the difficulties incident to thus trans
hitting the electric fluid have threatened to render
tina whole idea unavoidable. With a tuned