5 o6 THE POPULAR SCIENCE MONTHLY. 



continued to work, and from this grew the system now used in Paris. 

 Up to 1870 the above-described attempts, as well as many others (not 

 recounted), had proved a series of complete failures. Since that, how- 

 ever, several lines have been built in England that have continued to 

 work successfully ; and in Germany successful under-ground cables have 

 been laid down connecting together all of the principal cities of the 

 empire. The present complete system, as used between Liverpool 

 and Manchester, was constructed as follows : Iron or stoneware pipes 

 were laid from one to two feet below the level of the road-side with 

 flush-boxes coming to the surface every two hundred yards. Into 

 these was drawn a cable of gutta-percha-covered wires. The joints 

 were carefully made in the pipes, and they were smoothed inside to 

 prevent any possible abrading of the cable. The route was especially 

 selected through a low and marshy section of country, so that the 

 pipes were almost constantly filled with water this being the best 

 possible condition for the preservation of the gutta-percha. The pres- 

 ent European system dates from 1875. The cable is similar to that 

 used for submarine purposes. It consists of seven copper wires, each 

 coated with two layers of gutta-percha and two of Chatterton's com- 

 pound, and the whole covered with an armor of galvanized- iron wires. 

 This cable is laid in a trench by the road-side, and comes to the surface 

 only inside the telegraph-offices in the cities. Its cost was nearly 

 twenty times the cost of a well-built pole line. 



Although both the English and the German systems are success- 

 fully working lines of telegraph, they are far less efficient than pole 

 lines of the same length. The speed of working even the ordinary 

 instruments is limited ; serious trouble appears in attempting to use 

 fast-working machines, or automatic senders, and the use of the tele- 

 phone is impossible. 



I think these facts have sufficiently demonstrated that for long 

 lines of telegraph, stretching from city to city, here in America, pole 

 lines, which can be cheaply built, easily repaired, and where the wires 

 can be removed from the retarding influence of the earth and the in- 

 ductive influences on each other, are decidedly superior to under- 

 ground lines. 



Within our large cities the problem presented is somewhat differ- 

 ent. During the last few years the number of electric wires has 

 rapidly increased, especially since the introduction of the telephone 

 and electric light, and the probability is that the next few years will 

 show a further large increase. If these wires are run on poles, they 

 not only disfigure the streets, but seriously interfere with the opera- 

 tions of firemen in case of fire, as we have repeatedly seen during the 

 last few years. A cobweb of wires running over the house-tops re- 

 quires the linemen to continually tramp through the houses and over 

 the roofs, causing annoyance to the tenants and damage to the build- 

 ings. Moreover, wires fixed to house-tops are subject to removal at 



