Improvements in Effecting Telegraphic or Telephonic Communica- tion Through Submerged Cables, and in the Construction of Cables to be Used for this purpose.
Year: 1895

page_text: Date of Application, 24th May, 1895
Complete Specification Left, 24th Feb., 1896-Accepted, 4th Apr., 1896
PROVISIONAL SPECIFICATION.
Improvements in Effecting Telegraphic or Telephonic Communica-
tion Through Submerged Cables, and in the Construction of
Cables to be Used for this purpose.
We, WILLOUGHBY STATHAM SMITH, of 13 Courtfield Road, South Kensington,
Telegraphic Engineer, and WILLIAM PUDDICOMBE GRANVILLE, of 36 Oakfield
Road, Stroud Green, both in the County of Middlesex, Electrician, do hereby
declare the nature of this invention to be as follows:-
When electric communication is effected by the transmission of alternating or
intermittent currents through a submerged insulated conductor and the return or
outer part of the circuit is through the water in which the insulated conductor is
submerged the resistance of this outer or return part of the circuit may practically
be neglected in estimating the resistance of the whole circuit if the alternations or
interruptions of the current are comparatively slow but when very rapidly
alternating or intermittent currents are used such as those which pass when
telephonic communication is being carried on or when what is known as the rapid
Wheatstone transmitter is used we find that the resistance of this outer or return
circuit becomes very considerable owing to the small area of surrounding water or
earth which the current then traverses-the sectional area traversed by the current
becoming less and less as the rapidity of the alternations or interruptions increases.
To avoid this increase in resistance of the outer part of the circuit we closely
surround the insulation with an outer covering of copper or other non-magnetic
metal of high conductivity. One way in which we effect this object is as follows:
We first spirally lay round the core a ribbon or tape of metal of high conductivity
the ribbon or tape being brought into close contact with the insulating material so
as, as far as practicable, to exclude sea water from entering between them; and
secondly, we surround the ribbon with a number of wires of similar metal either
stranded together in groups or singly in the same way as in the construction of
wire ropes, the wires being laid either round a single core or in the case of a
multiple cable it may be around any number of cores. For the above purpose
high conductivity copper is specially suited. The so called earth connection at
either end would be made to the exterior of the cable.
As the main return current is with rapidly varying currents in close proximity
to the cuter insulation of the inner conductor and as copper is vastly superior to
water as a conductor of electricity the closely surrounding the insulated conductor
with an outer covering of copper will provide for currents of short duration a
path of low conductivity and thus for such currents will greatly reduce the
resistance of the outer part of the circuit.
Dated this 23rd day of May 1895.
WILLOUGHBY S. SMITH.
W. P. GRANVILLE.

page_text: COMPLETE SPECIFICATION.
Improvements in Effecting Telegraphic or Telephonic Communica-
tion Through Submerged Cables, and in the Construction of
Cables to be Used for this purpose.
We, WILLOUGHBY STATHAM SMITH, of 13 Courtfield Road, South Kensington,
Telegraphic Engineer, and WILLIAM PUDDICOMBE GRANVILLE of 36 Oakfield
Road, Stroud Green, both in the County of Middlesex, Electrician, do hereby
declare the nature of this invention and in what manner the same is to be performed
to be particularly described in and by the following statement:-
When electric communication is effected by the transmission of alternating or
intermittent currents through a submerged insulated conductor and the return or
outer part of the circuit is through the water in which the insulated conductor is
submerged the resistance of this outer or return part of the circuit may be
neglected in estimating the resistance of the whole circuit if the alternations or
interruptions of the current are slow but the resistance rapidly increases as the
rate of alternation increases and when transmitting instruments sending currents
which are rapidly alternating or intermittent are used, more especially if the
currents sent are such as those which pass when telephonic communication is being
carried on or when what is known as the rapid Wheatstone transmitter is used
we find that the resistance of this outer or return circuit becomes very considerable
owing to the small area of surrounding water or earth which the current then
traverses the sectional area traversed by the current becoming less and less as the
rapidity of the alternations or interruptions increases. To avoid this increase in
resistance of the outer part of the circuit we closely surround the insulation with
an outer covering of copper or other non magnetic metal of high conductivity.
One way in which we effect this object is as follows. We first spirally lay round
the core a ribbon or tape of metal of high conductivity the ribbon or tape being
brought into close contact with the insulating material and secondly, we surround
the ribbon with a number of wires of similar metal either stranded together in
groups or singly in the same way as in the construction of wire ropes, the wires
being laid either round a single core or in the case of a multiple cable it may be
around any number of cores. For the above purpose high conductivity copper is
specially suited. The so called earth connection at either end would be made to
the exterior of the cable.
As the main return circuit is with rapidly varying currents in close proximity to
the outer insulation of the inner conductor and as copper is vastly superior to water
as a conductor of electricity the closely surrounding the insulated conductor with
an outer covering of copper will provide for currents of short duration a path of
low conductivity and thus for such currents will greatly reduce the resistance of the
outer part of the circuit.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what
we claim is
---
1. The means hereinbefore described for effecting improved telegraphic or
telephonic communication through submerged cables.
2. The construction of telegraphic or telephonic cables with uninsulated copper
or other non-magnetic metal of high conductivity closely surrounding the insulation
substantially as described.
Dated this 20-1 2... Ր
1
WILLOUGHBY S. SMITH.
W. P. GRANVILLE.