. The Bell System technical journal . ithout 462 BELL SYSTEM TECHNICAL JOURNAL molybdenum. As a rule the maximum permeability was generallydecreased when a non-magnetic element was added and so were thesaturation values of induction. As our investigation was undertaken primarily for the purpose ofsearching for magnetic materials which could be used to advantagein the electrical communication field, it may be of interest to describea few of the principal uses to which some of these alloys have been put. Of the three groups of alloys which are of special technical interest,the permalloys are now
. The Bell System technical journal . ithout 462 BELL SYSTEM TECHNICAL JOURNAL molybdenum. As a rule the maximum permeability was generallydecreased when a non-magnetic element was added and so were thesaturation values of induction. As our investigation was undertaken primarily for the purpose ofsearching for magnetic materials which could be used to advantagein the electrical communication field, it may be of interest to describea few of the principal uses to which some of these alloys have been put. Of the three groups of alloys which are of special technical interest,the permalloys are now used extensively in electrical communicationcircuits. Perhaps its most spectacular use is for continuous loading ofsubmarine telegraph cable. The term loading is used in the electrical communication art todesignate a system of adding inductance to a transmission circuit forthe purpose of overcoming the unfavorable transmission characteristicsresulting from the electrical capacity of the circuit. This system has PERMALLOYLOADING TAPE. Fig. 21—Sample of submarine loaded cable, showing the loaded conductor. been used in telephone transmission circuits for over a quarter of acentury. The standard method used for telephone circuits, in whichinductance coils are placed at equally spaced intervals along the trans-mission line, was not considered practical for deep sea cables. Theonly suitable method from a mechanical standpoint was a continuousloading in which a magnetic material is distributed uniformly alongthe whole length of the cable. Before permalloy was developed thebest magnetic material available was iron. It could not be usedeconomically for long submarine cables because of its low permalloy having between 40 and 50 times the permeability ofiron in the range of magnetic field strength encountered in such cables,it was found that beneficial results could be attained and cables ofmore than five times the carrying capacity of the old type could bebuilt. The
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
