File:Bell telephone magazine (1922) (14570249047).jpg

Identifier: belltelephonemag19amerrich (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

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
f the No. 74 type heaterfuses let go on the Morse Battery panel. The variation in ground potential asmeasured between Boston and Keene, andwhich started around 9 A.M., was very er-ratic, sometimes reaching as much as 400volts positive and over 600 volts negative,which occurred around 11:30 a.m. It wasthis latter surge that caused 11 of the No.74 type fuses to blow at one time in theBoston office. The operation of most ofthe heat coils and carbons probably tookplace at this time, as there was a strongodor of ozone at the frame directly after.The potential changed at the rate of about100 volts per second and as we were notequipped to measure over 600 volts whenthe big surge came, it is possible, judgingby the rate of change, that the voltagereached somewhere near 800 volts negative,as the needle went off scale at 600 volts andremained off for a period of 4 or 5 seconds.This would be about the time required toreach 800 volts and return to 600 voltsagain. 194 Bell Telephone Quarterly JULY
Text Appearing After Image:
10 A.M. 9 A.M. 8 A.M. 7 A.M. FIG. 7 The record of the ground potential difference between Minneapolis, Minn., and Fargo,N. D., on the morning of March 24, 19^0 wave circuits on the transatlanticroutes were interrupted on Sundayand a number of days thereafter.Figure 9 shows graphically the pe-riods of interrupted service on thetransatlantic route on March 24 and25. Radiotelephone services to South America and across the Pacific wereaffected considerably less than thoseacross the Atlantic, and service to theCaribbean region through Miami, andcoastal and harbor radiotelephoneservices were practically free frominterruptions. Radio disturbances

Note About Images