. The telephone system of the British post office. A practical handbook . instruments in use by the Post Office today. A much neater and morecompact Gower-Bell telephone was designed, and this instrument is knownas the Post Office Telephone. It is considerably smaller than theordinary form, measuring 7 inches by 5 inches and projecting 6 diaphragm is stained black. The great objection to the china mouth-piece arrangement lies in the fact that moisture is condensed upon it,and when the telephone is much used most unpleasant odours arepresent. The transmitter is of the ordinary Gower
. The telephone system of the British post office. A practical handbook . instruments in use by the Post Office today. A much neater and morecompact Gower-Bell telephone was designed, and this instrument is knownas the Post Office Telephone. It is considerably smaller than theordinary form, measuring 7 inches by 5 inches and projecting 6 diaphragm is stained black. The great objection to the china mouth-piece arrangement lies in the fact that moisture is condensed upon it,and when the telephone is much used most unpleasant odours arepresent. The transmitter is of the ordinary Gower pattern. Its externalappearance is indicated in Figure 43. Connections. 55 The internal connections of the Post Office telephone are shown inFigure 44. The transmitter is connected to two flanges upon the inside ofthe case. A screw passes through the flange on either side; thus joiningthe microphone to the connections on the back board of the Figure 44. In this instrument two Bell receivers are shown joined up in induction coil is fitted beneath the case, and formerly had a resist-ance of s and 150 respectively for primary and secondary. A coilhaving from 9 to 12m and 25 is now used. The instrument is fitted with eight external terminals, which preciselycorrespond with the eight terminals fitted to the old Gower-Bell two central terminals are connected to the lines. From terminal 4the current passes to the end of the lever button, along it to the leftswitch lever through the upper contact to terminal i; from terminal 5 tothe centre of the right switch lever, through the upper contact to 3. Thusthe bell must be joined between i and 3. When the receivers are raisedthe left switch-arm joins them up, and the right switch-arm joins up themicrophone battery, which is connected between 5 and 6. Terminal 7 isused for the ringing battery, which is joined up in series with the micro-phone battery, which un
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Keywords: ., bookcentury1900, bookdecade1900, booksubjecttelepho, bookyear1901
