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History of the Atlantic Cable & Undersea Communications
from the first submarine cable of 1850 to the worldwide fiber optic network

Salient Features In Cable Design Since 1850
Submarine Cables Ltd

Introduction: In 1950, Submarine Cables Ltd published a 20-page booklet titled Submarine Telegraph Cable Centenary, commemorating the 100th anniversary of the laying of the first submarine cable from Dover to Calais in 1850. As well as a brief history of significant events in the industry, the booklet included a table of notable technical achievements in cable design.

Ten years later, in 1960, the company produced another booklet, titled One Hundred and Ten Years of Undersea Telecommunications. This updated the technical section of the first publication and added the advances of the 1950s, the most significant one being the introduction of repeaters, which made feasible long-distance undersea telephone cables across the Atlantic and elsewhere.

The introduction from the 1950 booklet and the two sets of technical data are reproduced below, providing an interesting insight into the design changes which improved the performance and longevity of submarine cables from 1850 to 1959.

--Bill Burns


The following information illustrates the various milestones which have marked the development of Submarine Telegraph and Telephone Cables. In order to appreciate the symbols used, the following explanation is made:-

In early days, most of the progress made in cable design centred round the type and weight of armouring. Iron wires, drawn to one of the standard sizes then available, were used, and the cable armouring was designated by two numbers separated by a stroke (e.g., 12/4). These indicated respectively the number of wires wrapped simultaneously round the cable and the gauge number of the wire. Where double armouring was used, this was expressed by two such symbols (e.g., 14/1, 10/6). Heavy armouring (not necessarily double armouring) is always used for cables near the shore where rocks and tides are encountered, but light armour is used for deep sea work. Armour of intermediate weight is used for “intermediate” conditions of depth. In due course heavily armoured cable (i.e., carrying No. 2 wires or larger) became known as Type A. Intermediate armour (i.e., Nos. 4 or 6 wires) was known as Type B and light armour (i.e., wires of No. 11 to No. 14 gauge) was known as Type C and finally as Type D.

This set of Telegraph Construction & Maintenance Company sample cables, circa 1900, shows the various designs of core available, the weights of armouring wire, and the assembly of the components into the finished cables of different type, as described above. Further details of the sample case, photographs of which were kindly provided by site visitor John Fleetwood, may be seen on this page.

A hundred years ago, the steel industry could not give cable manufacturers armour wire of high tensile qualities, but in present times deep sea cable is always armoured with wires having a tensile strength of from 65 to 95 tons per square inch, while low tensile (soft iron) wire of large section having a tensile strength of 35 tons per square inch is used for shallow water cables.

In due course, some cables were sheathed with armour wires each of which was protected with a fabric tape wrapping impregnated with bituminous compound. This was to minimise corrosion of the wires, and such armouring was referred to as “Taped Wires”. Helical wrappings of textile material were called servings.

When describing the size of the conductor and insulation, it is now customary to quote two numbers separated by a stroke (e.g., Core 130/130), the two numbers denoting the weights of the copper conductor and the insulation respectively, in lbs. per nautical mile (2,029 yards).

It will be noted that, in recent years, the main developments have been in transmission characteristics rather than in cable armouring.

Date Cable Made For Location Length
Types of Armour Used For Salient Features of Design to be Noted
1850 Brett & Co. Calais - Dover 25 unarmoured   Gutta percha covered wire only. Conductor comprised of solid copper.
1851 Crampton Calais - Dover 25 10/1    
1856 Atlantic Telegraph Co. Newfoundland - Cape Breton 85 12/4   12/9 First time stranded conductor used. Also heavier armour used at shore ends.
1859 Isle of Man Telegraph Co. Whitehaven - Isle of Man 36     Outer servings used for the first time, and adopted subsequently for all types except on stranded (shore end) armouring. It was used on Type C having served wires. In this case its use was to keep broken wires bound down. The use of so much fibrous material lead to the development of “Bread and Butter” type cable.
1860 French Govt. France - Algiers 450 10/00 called Type A 10/5 called Type

10/14 called Type C each wire Hemp served

First time an “intermediate” armour used. First time hemp protection of individual wires used. First time terminology “A”, “B” and “C” used.
1861 British Govt. Malta -Tripoli - Benghazi - Alexandria 1,331 12/3 12/5 18/11 First time core made as large as 400/400 and designated in this way.
1865 Atlantic Telegraph Co. Valencia - Heart's Content 1,896 12/3 x 5 over 10/13 No intermediate 10/13 each Wire Hemp served First time shore ends made by oversheathing Type C with another layer of armour and first use of Stranded armour on shore ends (to give weight combined with flexibility).
1866 Anglo-American Telegraph Co. Valencia - Heart's Content 1,853 12/0000 for heavy shore end 12/1 heavy intermediate 10/13 each wire
10/13. Remained favoured deep sea type for many years from this date. This was first use of multi-graded armouring.
1875/6 Eastern Extension Telegraph Co. Australia - New Zealand 1,283     9/13 plus 9 hemp yarns Major change in deep sea type. “Bread and Butter” type introduced. Bare wires laid alternately with hemp yarns. This completely replaced old Type “C”, i.e., hemp served wires.
1878 Eastern and South African Telegraph Co. Natal - Delagoa Bay - Zanzibar - Aden 3,852    

taped and
“Bread and Butter” (taped)

Taped steel wire first used for combating corrosion on deep sea cables
1879 Eastern Extension Telegraph Co. Penang - Malacca - Singapore -  Java 1,311     Teredo protection first used, i.e., Brass tape or Muntz metal applied to shallow water (shore ends) only.
1881 Atlantic Telegraph Co         First time taut wire paid out simultaneously when laying, in order to give a correct indication of percentage of slack laid.
1891 Eastern Telegraph Co         “Bread and Butter” type abandoned in favour of close wire sheathing (Nos. 13 and 14 high tensile wire used).
1893 African Direct Telegraph Co Bonny - Cameroons
Lisbon - Azores
14/2 over 10/6 10/6   First use of double armouring involving two layers of solid wires. Shore ends made by oversheathing intermediate.
1894 Anglo-American Telegraph Co Valencia - Heart's Content 1,848 Following cables:
All armouring conventional
Introduction of short lay heavy wires (00) for shore end protection.
1900 Deutsch-Atlantische Telegraphen-Gesellschaft Borkum - Fayal - New York 4,161     First use of twin core shore ends for “Sea Earth” to eliminate local interference, at terminals (10 miles at New York and 1 mile at Borkum).
1902 Pacific Cable Board Vancouver - Fanning Island 3,458     Longest section ever laid (part of 7,837 n.m.).
1902 Pacific Cable Board Lake Constance       First coil loaded Submarine Telephone Cable.
1902 Danish Govt Danish Coast       First continuous inductively loaded (soft wire) cables.
1913 Eastern Extension Telegraph Co. Penang - Colombo 1,407     First use of Tri-core shore ends  - to provide separate sending and receiving earth connections.
1919 Western Telegraph Co. Ascension - Rio de Janeiro 2,103    

Lead covering first used for Beach cable, to protect the Gutta Percha from oxidising while not under water.

1921 Cuban-American Telephone and Telegraph Co. Key West - Havana (3 Cables) 3 x 103     First Coaxial (voice frequency) telephone cable incorporating continuous iron wire loading and employing a short lay copper tape as outer conductor.
1923 Eastern Extension Telegraph Co Colombo - Penang 1,459     First use of rubber insulated lead covered shore ends for tropical climates. Afterwards this became a regular feature in the tropics.
1924 British Post Office Aldeburgh - Domburg 82     First Dry-core paper insulated, lead-covered telephone cable to be laid under the sea.
1924 Western Union Telegraph Co. New York - Fayal 2,329     First high speed loaded telegraph cable, using continuous loading of Permalloy tape.
1928 Ditto Bay Roberts - Fayal 1,341     The most recently laid Atlantic cable [as of 1950] - High speed - Continuously loaded with Mumetal wire - Taper loaded at ends to permit of Duplex working.
1930 American Telephone & Telegraph Co Key West - Havana       First Paragutta (improved dielectric) carrier telephone cable.
1942 British Post Office Anglesey - Isle of Man 43     First use of submerged repeater in Paragutta Co-axial carrier telephone cable.
1944 Ditto Southbourne - Longues No. 1 105     First K-gutta carrier telephone cable.
1945 Ditto Cuckmere - Dieppe No. 1 70     First Telcothene (superior dielectric) carrier telephone cable.
1947 Ditto Aldeburgh - Domburg 83     First Telecothene semi air space co-axial carrier telephone cable. (1.7” diam.).
1 repeater inserted 1957 for 180 circuits.
1950 Netherlands and Danish Telegraph Administrations Oostmahorn - Romo (2 Cables) 2 x 142     First Submarine Cables to be planned and laid with three 2-way repeaters. Repeaters replaced 1956 by 7 for 120 circuits.
1950 Great Northern Tel. Co. England - Denmark 307     Polythene coaxial for carrier telegraphy. 2 repeaters inserted 1954, replaced 1957 by 6.
1954 Post Office Scotland - Norway 307     Polythene coaxial with 7 repeaters.
1955 American Tel. & Tel. Co. and Post Office Oban, Scotland - Newfoundland 1,941     Each with 51 one-way repeaters for 36 channels. 92 % of cable made by S.C. Ltd.
1956 American Tel. & Tel. Co. and Post Office Oban, Scotland - Newfoundland 1,943    
1956 American Tel. & Tel. Co. and Post Office Newfoundland - Nova Scotia 271     With 14 repeaters for 60 circuits.
1957 Western Electric Co. Point Arena, U.S.A. - Honolulu (two cables) 2,197
    Each with 57 one-way repeaters.
43 % of cable made by S.C. Ltd.
1959 American and Eastern Tel. & Tel. Co. Newfoundland - Penmarc'h, France (two cables) 2,206
    Each with 57 one-way repeaters.
1900 n.m. made by S.C. Ltd.
1959 American and Eastern Tel. & Tel. Co. Newfoundland - Nova Scotia 280     With 14 repeaters.

Last revised: 18 February, 2010

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