164 Telephone Systems of the Continent of Europe 



M I M 2 . The cores have curved pole-pieces p 1 p 2 , between which 

 revolves the soft-iron armature A driven by a pinion, toothed 

 wheel and crank as shown. The wheel is loose on the crank 

 spindle until caught by the pin T engaging with the recessed 

 collar R, when it is revolved, the spring s compressed, and spring 

 contact o removed from the fixed contact i to the fixed contact 

 j, the result being that the bell is cut out from the line when the 

 crank is in motion, and the generator coils when it is at rest. 

 Each revolution of the soft-iron armature induces currents in the 

 coils, the direction of which is determined by the approach or 

 retrogression of the armature to or from the pole-pieces. It will be 

 seen that the connections are arranged so that the currents of the 

 same name generated simultaneously in the two coils join at x, and 

 go out to line together. As a departure from ordinary practice in 

 a direction which has proved singularly sterile in innovation, this 

 magneto is interesting, while the abolition of moving coils and 

 contacts should operate on the side of economy in maintenance. 



OUTSIDE WORK (LOCAL) 



As regards Paris, the whole of the work practically is under- 

 ground, chiefly in the sewers. In the centre of the city, overhead 

 wires do not exist at all, and there are but few to be seen anywhere 

 within the fortifications. But immediately these are passed, pole 

 routes begin, and in the suburbs aerial work is exclusively used. 

 Formerly, wires insulated with gutta-percha were twisted in pairs 

 and made up into small cables, which were hung on brackets from 

 the sewer roofs or walls. These were found liable to various 

 interferences, attacks by rats, &c. ; and now the cables, which are 

 as a rule much larger than the older ones, and mostly insulated 

 with paper, are always laid in strong sheet- iron troughs with 

 tightly fitting lids, for which there is fortunately room. A good 

 many Fortin-Hermann cables exist, and have proved exceedingly 

 satisfactory in service for the long-distance connections. Each 

 conductor is strung throughout its length with birch beads, the 

 wood being sound and dry, one centimeter long and three centi- 

 meters in diameter. Two conductors are then twisted together, 

 and as many pairs as are required drawn into a leaden tube to 



