The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 554
own in question is classifiedas coming under division A, B or C, according as the ratio ofthe use of telephones with a plant ten to fifteen years old hasbeen 10 per cent, or over; 6 to 8 per cent. ; or under 6 per cent.of the number of inhabitants respectively. With new and improved plants it is… … 0 2. 4 6 5 10 12. , /4 lb- /S 20 Fig. 4S5.—Ratio Curve showing future Development of Population or other such increases in ratio are unlikely to occur in the twohigher classes the towns may be reduced in class. A ratiocurve is next made out showing the increase in the ratio up tothe future twenty…
Telephone
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