In the 1920s, communicating across oceans remained painfully slow. While telephone networks were rapidly expanding across continents, underwater communication was trapped by fundamental technical limitations. The first submarine telegraph cables could transmit only a few words per minute, creating a bottleneck that frustrated growing international commerce and communication needs.
At Bell Labs, Oliver Buckley and his team were tasked with solving this seemingly impossible engineering challenge. Their work would span nearly two decades, from 1925 to 1942, as they pushed the boundaries of materials science, manufacturing precision, and engineering design to create cables that could operate reliably in one of Earth's most hostile environments.
"A submarine cable requires a degree of care and precaution in engineering such as is required in few other situations" (Buckley, 1942).
The breakthrough came in September 1924, when Buckley's team achieved what many thought impossible. Their experimental cable between New York and the Azores transmitted messages at an unprecedented 1,920 letters per minute—more than triple the speed of existing cables. This wasn't just about faster communication; it represented a fundamental reimagining of how underwater cables could work.
The secret lay in a revolutionary material called permalloy, invented by G.W. Elmen at Bell Labs. This nickel-iron alloy possessed extraordinary magnetic properties that dramatically improved signal transmission. The composition was precise:
"approximately 78½% nickel and 21½% iron" (Buckley, 1925)
The impact was immediately clear to Buckley:
"The permalloy-loaded cable marks a new era in transoceanic communication" (Buckley, 1925)
What made Buckley's approach so revolutionary wasn't just the material—it was his understanding of the extreme engineering challenges. The permalloy had to be applied as a thin layer wrapped around the copper conductor in tape form. The specifications were precise:
"a thin layer of permalloy wrapped around the copper conductor" in tape form just "0.006 inch thick and 0.125 inch wide" (Buckley, 1925)
But here's where the real engineering brilliance emerged: permalloy is incredibly sensitive to mechanical stress.
"Strain of deformation applied to it will modify its magnetic characteristics, and very great changes in its permeability for small magnetizing forces may be produced by strains well within the mechanical elastic limit" (Buckley, 1928)
This meant that the crushing pressure of deep ocean deployment could destroy the cable's performance entirely.
Buckley's team solved this with remarkable ingenuity. They annealed the permalloy after wrapping it around the copper conductor, then vacuum-impregnated the entire assembly with a semi-fluid compound. The heat treatment was precisely controlled:
"approximately 900° C" (Buckley, 1928)
This compound would flow under pressure to protect the delicate permalloy from deformation, ensuring the cable maintained its performance even at crushing depths.
The insulation presented its own set of problems. Traditional submarine cables used gutta-percha, a rubber-like material derived from tropical trees. Buckley's team had to balance electrical performance with mechanical protection:
"The thickness of gutta-percha must be sufficient to insure the integrity of the insulation at all points" (Buckley, 1925)
They were engineering for extreme conditions. The cables had to survive at depths of over 15,000 feet, where every decision about insulation thickness became a careful balance between electrical performance, mechanical protection, and economic reality.
"2,500 fathoms" (Buckley, 1942)
By 1928, Buckley's cables were revolutionizing global communications. The success of the New York-Azores cable had sparked a worldwide transformation.
"Demands for other high-speed loaded cables quickly followed the successful demonstration of the New York-Horta cable" (Buckley, 1928)
The impact was staggering. Two cables were now doing the work of sixteen:
"The traffic-carrying capacity of these two transatlantic loaded lines is nearly as great as that which was previously provided by the sixteen older non-loaded cables" (Buckley, 1928)
The key to this success lay in the remarkable properties of permalloy. The material used in the New York-Horta cable had dramatically better magnetic properties than anything previously available:
"a permeability of about 2,300" (Buckley, 1925)
This compared to the iron wire used in earlier cables, which had a permeability of only:
"about 115" (Buckley, 1925)
This twenty-fold improvement in magnetic properties translated directly into dramatically better signal transmission.
But Buckley didn't stop there. By 1928, his team had developed even better permalloy compositions. The newer cables used an improved alloy:
"about 80 per cent nickel, 17.5 per cent iron, 2 per cent chromium and 0.5 per cent manganese" which achieved "an initial permeability of about 3700" (Buckley, 1928)
The manufacturing process required unprecedented precision. The permalloy loading material had to be applied with tolerances measured in thousandths of an inch:
"a closely wound helix surrounding the conductor" (Buckley, 1928)
Different cables used slightly different specifications. The Horta-Emden cable used tape:
"0.0059 X 0.098 inch" (Buckley, 1928)
While the New York-Bay Roberts cable used tape:
"0.0055 inch" thick (Buckley, 1928)
This level of precision wasn't just about performance—it was about reliability. As Buckley explained the fundamental difference from earlier cables:
"A cable of the ordinary type, without loading, is essentially, so far as its electrical properties are concerned, a resistance with a capacity to earth distributed along its length" (Buckley, 1925)
The permalloy loading fundamentally changed this equation, creating cables that could handle much higher frequencies and data rates.
By 1942, Buckley's perspective had evolved considerably. Now president of Bell Labs, he was thinking not just about telegraph cables, but about the future of transoceanic telephony. The challenges were immense:
"Whether viewed as an extension of frequency from 100 cycles to the 3000 cycles needed for high grade telephony, or as an extension of distance, the step was a formidable one" (Buckley, 1942)
The 1942 vision required even more advanced materials. Instead of gutta-percha, Buckley's team developed paragutta, a more sophisticated insulation material:
"a mixture of specially purified and deproteinized rubber, deresinated balata or gutta percha, and some wax" (Buckley, 1942)
This new material had superior electrical properties:
"a dielectric constant 15 per cent lower than the gutta percha" and "leakance at telephone frequencies about one-fifteenth as great" (Buckley, 1942)
For the magnetic loading, they moved from permalloy to perminvar, an alloy with improved characteristics:
"very low hysteresis, which helps in preventing distortion of speech due to magnetic modulation" (Buckley, 1942)
The proposed cable would use:
"four layers of very thin perminvar tape" (Buckley, 1942)
The proposed transatlantic telephone cable represented an enormous leap in scale and complexity. The cable specifications were unprecedented:
"516 pounds of copper per mile insulated with 370 pounds of paragutta, surrounded by a return conductor of 600 pounds" (Buckley, 1942)
This was:
"much heavier than any that had previously been laid in great depths" (Buckley, 1942)
The technical challenges were staggering. The cable would need to operate at extreme signal levels:
"as high attenuation as would be permitted by considerations of noise at the receiving end and usable power at the sending end" with "a permissible overall attenuation as high as 165 db for a top frequency of 3,000 cycles" (Buckley, 1942)
Buckley's team didn't just theorize—they tested. In 1930, they manufactured a 20-mile test section and took it to the Bay of Biscay, where:
"a depth of 2,500 fathoms was conveniently available" (Buckley, 1942)
The cable was:
"paid out on the sea floor and its open-end impedance measured over the telephone range of frequencies" (Buckley, 1942)
The results were encouraging:
"Measurements of impedance both from the ship and from the shore showed the cable to be quite unimpaired both at 2½ miles depth and after recovery and relaying in shallow water" (Buckley, 1942)
By 1942, after nearly two decades of pushing the boundaries of submarine cable technology, Buckley had developed a realistic understanding of both the potential and the challenges of his work. His reflections reveal an engineer who understood that innovation required not just technical brilliance, but also realistic assessment of risks.
"Submarine cables, like all things that go to sea, can never be completely dissociated from some chance of disaster" (Buckley, 1942)
This wasn't pessimism—it was the wisdom of an engineer who had spent his career wrestling with ocean deployment challenges.
Yet Buckley remained optimistic about the future:
"I am optimistic that by a sufficiently thorough job of cable manufacture and a well planned program of trials, the hazards can be reduced to an acceptable degree" (Buckley, 1942)
He understood that progress required both bold vision and careful execution:
"It will take some years to reach this point, and at best it must be expected that some degree of hazard will still remain" (Buckley, 1942)
Buckley's work at Bell Labs represented more than just technical achievement—it was a masterclass in systematic innovation. From the 1925 breakthrough with permalloy to the 1942 vision of multi-channel telephone cables, his approach combined rigorous scientific method with practical engineering wisdom.
The materials science alone was revolutionary. The progression from basic iron loading to permalloy to perminvar represented a continuous quest for better magnetic properties. The evolution from gutta-percha to paragutta showed similar innovation in dielectric materials. Each improvement built upon the last, creating cables that could handle ever-higher frequencies and data rates.
Buckley's work required deep understanding of the ocean environment where his cables would operate. He recognized that the ocean floor presented unique engineering challenges that had to be accounted for in every design decision.
"the temperature at the bottom of the ocean is nearly constant" (Buckley, 1942)
His team had to design for cables that would need to withstand:
"considerable vibration and perhaps to heavy blows in the course of laying and lifting" (Buckley, 1942)
This understanding of ocean conditions influenced every aspect of their cable designs, from materials selection to manufacturing processes. The cables had to survive not just the initial deployment, but decades of operation in an environment where repair or replacement would be extremely difficult and expensive.
Oliver Buckley's rise to president of Bell Labs in 1940 was the culmination of a remarkable career that had already transformed global communications. His submarine cable work demonstrated the qualities that would make him an exceptional leader: technical brilliance, systematic thinking, and the ability to see beyond immediate challenges to long-term possibilities.
Under his leadership, Bell Labs would continue to push the boundaries of what was possible. The transistor, information theory, and countless other innovations would emerge from the laboratory culture he helped create. But his submarine cable work remains a testament to what can be achieved when rigorous engineering meets bold vision.
Looking back at Buckley's submarine cable work, we see more than just a series of technical achievements. We see the story of how systematic engineering and bold vision helped connect the world. From the first permalloy-loaded cable in 1924 to the multi-channel telephone systems he envisioned in 1942, Buckley's work laid the foundation for the global communications networks we take for granted today.
His legacy reminds us that true innovation requires understanding both the technical challenges and the practical constraints. In Buckley's case, those constraints included the vast, hostile depths of the ocean, the limitations of available materials, and the economic realities of large-scale deployment. Through careful engineering, systematic experimentation, and realistic assessment of challenges, he and his team at Bell Labs found ways to overcome these obstacles.
The cables that carry our internet traffic across the oceans today owe their existence to the foundation Buckley laid in those crucial decades of the 1920s, 1930s, and 1940s. His work stands as a reminder that the most important innovations often come from those who dare to tackle the seemingly impossible challenges of their time.
Buckley, O. E. (1925). The Loaded Submarine Telegraph Cable. Bell System Technical Journal, 4(3), 355-374.
Buckley, O. E. (1928). High-Speed Ocean Cable Telegraphy. Bell System Technical Journal, 7(2), 225-267.
Buckley, O. E. (1942). The Future of Transoceanic Telephony. Bell System Technical Journal, 21(1), 1-24.