The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 346
it, and automatically regis-ters a curve, which shows at a glance the amount of current which has been used at anytime of the day. This curve, being proportional to thenumber of calls and connections (if the lines are in goodorder), acts as a check on the record of calls taken directlyon certain… … zra Cop**r MicakUft Fig. 320.—Scale §. Copper 318 PRACTICAL TELEPHONE HANDBOOK Fig. 319 shows a section of one of the alarm fuse holdersin position on a slate base, and Fig. 320 gives a plan of twoof them. A strip of micanite (which is an insulating sub-stance composed of mica and shellac), If…
Telephone
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