All About Inventions and Discoveries
The Romance of modern scientific and mechanical Achievements

iö2 All About Inventions In Great Britain such lengthy trunk roads are impossible, owing to lack of opportunity. But there is telephonic conversation between various parts of the country and Paris, while previous to the out- break of war Brussels was linked up with England. So far as distance is concerned, this may not com- pare with the overland of the United States, but at the same time it is decidedly noteworthy, because it introduces a length of sea-cable forming the middle section between the respective land spans. Perhaps the most outstanding telephone achieve- ment in England is the underground circuit which is being provided between London, Birmingham, and Liverpool. This undertaking was rendered necessary owing to the growth of the traffic be- tween the three points. Fifty-two circuits are pro- vided from the fifty-two pairs of wires forming the cable, plus a further twenty-six circuits, represent- ing one circuit per two pairs of wire, formed by what is known as “ phantom ” circuit working. The total length of this underground cable is 202I miles, com- prising the first section to Birmingham, no J miles, and thence to Liverpool, 90 miles. At intervals of two and a half miles Pupin loading coils, similar to those used upon the United States transcontinental line and, in fact, built by the manufacturing branch of that organisation, are inserted. The weight of the wire used in this underground cable varies from 300 lb. per mile of wire for the two pairs forming the central core, 200 lb. per mile for each wire of the first layer of fourteen pairs of wires, and 150 and 100 lb. per mile for the thirty-six outer circuits, the whole being enclosed in a sheath of lead. The aver-