The Development of Submarine Telecommunications Cables (1850s-1950s): A Primary Source Analysis

Introduction

This analysis examines the evolution of submarine telecommunications cables through primary source material from Bell System Technical Journal publications spanning 1925-1951. During this period, telecommunications technology underwent rapid transformation - from basic telegraph cables to complex telephone systems with submerged repeaters. This research specifically focuses on the materials, engineering decisions, and technical innovations that enabled transoceanic communication.

The documented period captures several critical transitions:

• The shift from early rubber and gutta percha insulation to lead-based sheathing
• The development of improved insulating materials like paragutta and polyethylene
• The introduction of submerged repeaters and carrier systems
• The competition between submarine cables and emerging radio technology

Academic Citations

Buckley, O. E. (1928). High-Speed Ocean Cable Telegraphy. Bell System Technical Journal, 7(2), 225-267.

Buckley, O. E. (1925). The Loaded Submarine Telegraph Cable. Bell System Technical Journal, 4(3), 355-374.

Affel, H. A., Gorton, W. S., & Chesnut, R. W. (1932). A New Key West-Havana Carrier Telephone Cable. Bell System Technical Journal, 11(2), 197-212.

Gilbert, J. J. (1951). A Submarine Telephone Cable with Submerged Repeaters. Bell System Technical Journal, 30(1), 65-87.

Burns, R. M. (1936). Corrosion of Metals—II. Lead and Lead-Alloy Cable Sheathing. Bell System Technical Journal, 15(4), 603-625.

Strategic Goals & Business Drivers

The primary motivation for submarine cable development was the growing demand for transoceanic communication capacity. From Buckley (1928):

“Such an extension of facilities for transoceanic communication would be expected to have a pronounced effect on both the cost of communication and the amount of communication between continents and, indeed, such an effect has already been experienced, significant reductions in rates having been made within the past year.”

The technology had to evolve to meet increasing capacity demands. From Hitchcock (1926):

“Although the two circuits provided by the cables represented a great improvement over the previous condition as regards the quality of the service rendered and the number of messages which could be handled, it was realized that they would soon prove inadequate to handle the heavy summer business, for which eight or ten circuits would be required in a relatively short time.”

Cost Considerations

The economic factors driving cable development were substantial. From Hitchcock (1926):

“To provide for such a large increase by the laying of additional cables was deemed impracticable, as the cost would be excessive. Furthermore, in water of this depth—3,000 feet—it is important that cables be laid at least a mile or two apart, so that in the event that trouble develops on one, it can be repaired without disturbing any of the others.”

From Gilbert (1951):

“Servicing of the repeater would be in the nature of a cable repair, and the repair of a submarine cable is something not to be sought after. The procedure is apt to be expensive and time consuming, due to circumstances beyond control such as bad weather or lack of availability of a repair ship.”

Material Evolution

Early Materials (Pre-1880)

From Buckley (1928):

“The earliest telephone cables were of the type employed in telegraph practice, the individual wires being insulated with rubber or gutta percha and the core covered with a rubber or textile sheathing.”

Editor’s note: the artifact attributes this passage to Buckley (1928); it appears in R.M. Burns, BSTJ 1936, pp. 603–604.

Lead Adoption and Development (1880-1912)

From Burns (1936):

“The first lead-covered telephone cables were made by David Brooks, Jr., and were installed in the year 1880. These consisted of cotton-covered wires drawn into a lead pipe—a moisture-proofing compound of rosin and paraffin being forced afterward into the pipe and allowed to solidify by cooling.”

The composition evolved over time:

“Beginning in 1882 telephone cables were sheathed with an alloy of 97 per cent lead and 3 per cent tin, which continued to be the standard composition for cable sheathing in the Bell System until 1912. The general adoption of the present standard alloy of lead with 1 per cent antimony in that year has afforded substantial economies and a sheathing of high resistance to fatigue cracking.”

Rationale for Lead Selection

The choice of lead was based on specific technical requirements. From Burns (1936):

“While the choice of lead as a cable sheathing material was dictated primarily by physical requirements, notably its adaptability to extrusion, corrosion resistance has been a large factor undoubtedly in its successful use. It has long been recognized that lead is one of the least corrodible of metals.”

Engineering Specifications

The exact composition was carefully controlled. From Burns (1936):

“The lead which best lends itself to the manufacture of lead-antimony cable sheathing is a high-copper, low-bismuth chemical grade of lead of the following nominal composition:

Silver 0.002 to 0.02%
Copper 0.04 to 0.08%
Bismuth 0.005% (max.)
Arsenic, antimony and tin together 0.002 (max.)
Zinc 0.001 (max.)
Iron 0.0015 (max.)
Lead (by diff.) 99.90”

Later Material Developments (1930s-1950s)

New synthetic materials emerged. From Affel et al. (1932):

“The insulating material in this case was paragutta, which had been recently developed by the Laboratories, and which possessed electrical characteristics and stability much superior to gutta-percha.”

By 1951, further advances had been made. From Gilbert (1951):

“The cable has a copper return, as in the case of the earlier installations, but differs from them in being insulated with polyethylene. It also involves some new principles of design that render the cable circuit less subject to change of electrical characteristics due to laying stresses.”

Environmental Challenges and Protection

Corrosion Protection

From Burns (1936):

“It is not the practice of the Bell System to bury lead-covered cables directly in the soil without the use of a protective coating. Recognition of the corrosion hazard involved in such construction is one of the considerations which led to the use of conduit for the housing of even the first cables which were placed underground.”

Shoreline Considerations

Coastal areas presented unique challenges. From Gilbert (1951):

“Experience with existing cables which land in Havana Harbor indicate that considerable deterioration of armor takes place in this locality and there is also the anchor menace. In addition, closeness to an existing carrier frequency cable might have given rise to undesirable crosstalk.”

Deep Water Installation

Deep water installation required special consideration. From Gilbert (1951):

“The decision to place the repeater on the ocean bottom resulted in special requirements on the structure the first of which is that it be capable of resisting the considerable hydrostatic pressure that is encountered in deep water.”

Major Geographic Deployments (1920-1951)

Key West-Havana System

• 1921: Three continuously loaded cables laid
• 1931: New carrier telephone cable installed
• 1950: Submarine telephone cable with submerged repeaters installed

New York-Azores (Horta) Connection

• September 1924: First permalloy-loaded ocean telegraph cable
• Operated by Western Union Telegraph Company

Pacific Routes

• 1902: Original Bamfield-Fanning Island-Suva cables laid
• 1926: New loaded cables installed by Pacific Cable Board

European Connections

• 1926: Horta-Emden cable laid by Deutsch Atlantische Telegraphengesellschaft
• 1926: New York-Bay Roberts-Penzance cables laid by Western Union

Other Notable Deployments

• 1923: Los Angeles-Catalina Island cables (replacing 1920 radio system)
• 1926: Cocos Island-Perth (Australia) cable

Competition with Radio

The emergence of radio created uncertainty in the cable industry. From Buckley (1928):

“With the birth of this new child of science arose the question as to whether the art of telegraphing over cables would not ultimately die. But radio too required time to grow, and it is only within very recent years that there has been occasion for serious concern as to the future of the older art. Now a new advance has been made on the side of the cables and the race for supremacy in transoceanic communication has taken a new turn.”

System Performance and Reliability

By 1951, the technology had proven itself. From Gilbert (1951):

“Since the installation of the new system, it has been subjected to comprehensive tests involving measurement of noise and intermodulation between channels as well as precise measurements at numerous frequencies of net loss of the repeatered cables at intervals of time. The system has proved to be very stable and has met the requirements laid down for it.”

The importance of reliability was paramount. From Gilbert (1951):

“Nothing unfavorable to the submerged repeater has made itself felt; but, in accordance with conservative submarine cable tradition, its performance will be critically observed over a period of time.”

Conclusion

The evolution of submarine cable technology between the 1850s and 1950s represents a continuous drive to improve communication capacity, reliability, and economic efficiency. The transition from early materials to lead sheathing, and later to synthetic insulations, was driven by both technical requirements and practical considerations of manufacturing and installation. The introduction of repeaters and carrier systems marked a significant advance in capacity, while improved materials and installation techniques enhanced reliability and longevity.