518 POPULAR SCIENCE MONTHLY 



NOTES ON" THE DEVELOPMENT OF TELEPHONE SERVICE 



By FRED DELAND 



PITTSBURGH, PA. 



IX. Telephone Line Construction. 



IN 1876 the wires used for telegraph, circuits were usually of iron 

 or steel, because the tensile strength permitted of long spans and 

 comparatively long sag. At that period hard-drawn copper line wire 

 was unknown, and it is problematical whether the volume of traffic 

 passing over the average telegraph wire at that time, outside of the 

 main trunk lines, would have justified the heavy initial investment 

 required to string copper circuits. ThUs it came about that iron and 

 steel wires were naturally adopted for telephone lines. 

 About that time George B. Prescott wrote that 



a very short experience with, copper line wires both in this country and in 

 Europe, proved that this metal was altogether unsuitable for the purpose, its 

 sole recommendation consisting in its superior conductivity, and it was, there- 

 fore, soon replaced by iron wire of large diameter. 



But T. B. Doolittle proved how fallacious that theory was, by 

 producing a hard drawn copper wire in 1877, that, as stated in Chapter 

 V., proved of inestimable value to telephone interests the world over. 



This failure on the part of soft drawn copper wire to satisfactorily 

 serve as line wire was due to the unpleasant habit it had of not staying 

 where it was placed; it lacked the physical stamina to support itself, 

 and would break with its own weight. This fact was well known to 

 telephone men. Yet few perceived the merit in Mr. Doolittle's im- 

 provement, or took kindly to it until forced to do so by later conditions. 

 In 1880, three years after Mr. Doolittle's experimental hard drawn 

 copper line had been strung in Ansonia, Connecticut, a telephone line 

 gang started to string a toll circuit between Hartford and New Britain, 

 but completed less than five miles. This circuit consisted of one No. 

 18 soft drawn copper c office ' wire, having a double braided cotton 

 covering saturated with paraffine; but by reason of the long spans 

 between the poles the sag was sufficient to cause the small soft wire to 

 break with its own weight. Thus, after spending several days in 

 rejoining broken ends, the circuit was abandoned, and iron wire strung 

 in its place. 



In cities and wherever the iron circuits were subjected to the de- 

 structive effects of atmospheric action, especially where much bitu- 

 minous coal was used, oxidization shortened the life of the circuits in 



