File:Bell telephone magazine (1922) (14753812744).jpg

Identifier: belltvol20elephonemag00amerrich (find matches)
Title: Bell telephone magazine
Year: 1922 (1920s)
Authors: American Telephone and Telegraph Company American Telephone and Telegraph Company. Information Dept
Subjects: Telephone
Publisher: (New York, American Telephone and Telegraph Co., etc.)
Contributing Library: Prelinger Library
Digitizing Sponsor: Internet Archive

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lso causes thesubscribers line to become noisy orperhaps to fail altogether. Becauseof the addition of new subscribers,changes in residence of old subscrib-ers, and service changes, about fourhundred million feet of new drop wireare needed by the Bell System eachyear. Obviously, low cost is an im-portant requirement. The Evolution of Drop W ire 1 HE use of drop wire is almost asold as the telephone art itself. Worktoward improving its performance hasbeen carried on since the earliestdays; but the major improvementshave been made during the past fifteenor twenty years, as a result of generaladvances in chemical and metallurgi-cal processes. Let us pick up the developmentabout the year 1928. By this time ithad become evident, from analyses offield results and by Laboratories testsof the product, that a major sourceof trouble with the then standard wirewas failure of the insulation at thepole and building attachments, be-tween which the wire was suspended. i9 ^4 1 Evolution by Design 137
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Protective Apparatus at Subscribers Premises Near the point where the drop wire enters a building, a protective device is installed to dis-charge harmlessly any stray current of excess voltage which might accidentally be on theoutside telephone ivires. The new one-piece porcelain protector at the right is cheaper tomake and is better adapted for mounting in homes of modern construction than is the protector of older design It was known that this was due pri-marily to the fact that as the rubberaged, it gradually lost part of its elas-ticity and strength and finally becamebrittle. Development work was un-dertaken with two objectives: to de-sign a suspension attachment whichwould distribute the gripping pressureof the attachments over a wider areaof the rubber, and to obtain a rubberhaving better physical characteristics.Up to that time, the suspension de-vice had consisted of a porcelain knobattached to a bracket, the wire beinglooped around the knob and securedby a tie wire. A clampin

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