High-Speed Ocean Cable Telegraphy

The invention of permalloy and its application to submarine cables have led to the installation of transoceanic cables of many times the traffic-carrying capacity of the former non-loaded cables. This paper relates briefly the history of the development of permalloy-loaded cables and discusses certain outstanding problems concerned with their design, construction and operation. In a concluding general survey the field of usefulness of loaded submarine telegraph cables is considered. To a considerable extent the paper is a critical summary of material previously published by members of the staff of the Bell Telephone Laboratories. Its scope is indicated by the sub-titles as follows: Loaded Cables Now in Service Historical Remarks Permalloy and Its Application to Cables Principles of Design of Loaded Cables Principles Involved in Operation Apparatus for Restoration of Signals Apparatus for Automatic Operation Electrical Measurements of Loaded Cables A General Survey OLTA devised his famous pile in 1799. Less than 60 years later, in 1858, the first telegraph message was sent over an Atlantic cable. Now nearly 70 years have passed since the remarkable feat of transatlantic telegraphy was first accomplished. Although the art of cable telegraphy may therefore be considered old, it cannot be said ever to have stopped growing. At all periods of its growth it has offered an interesting field for technical endeavor. An added interest was attached to it a little more than 25 years ago when Marconi, by his famous demonstration of transatlantic radio telegraphy, introduced a competitor.