History of the Atlantic Cable & Submarine Telegraphy - Salient Features In Cable Design Since 1850

	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

SALIENT FEATURES IN CABLE DESIGN SINCE 1850

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 Nautical Miles	Types of Armour Used For			Salient Features of Design to be Noted
Date	Cable Made For	Location	Length Nautical Miles	Shallow Water	Intermediate Depths	Deep Sea	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 served	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			11/13 taped and 9/13 “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	180 1,053	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 2,211				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 2,205				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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