Heroes of the Telegraph/Chapter 4 > 자유게시판

It was due to the brilliant promise he displayed, as much as to the influence of his father, that at the age of twenty-two he found himself wearing the gown of a learned professor in one of the oldest Universities in the country, and lecturing to the class of which he was a freshman but a few years before. William began his course at the same college in his eleventh year, and was petted by the older students for his extraordinary quickness in solving the problems of his father's class. After Cooke and Wheatstone had introduced their working telegraph in 1839; the idea of a submarine line across the Atlantic Ocean began to dawn on the minds of men as a possible triumph of the future. Sensible men doubted whether the cable had ever 'spoken;' but in addition to the royal despatch, items of daily news had passed through the wire; for instance, the announcement of a collision between two ships, the Arabia and the Europa, off Cape Race, Newfoundland, and an order from London, countermanding the departure of a regiment in Canada for the seat of the Indian Mutiny, which had come to an end.

In this way hundreds of single wires would be gathered into small and inoffensive cables, and the enormous wooden structures would be replaced by small cable supports of brick or iron. Sir William Thomson, the greatest physicist of the age, and the highest authority on electrical science, theoretical and applied, was born at Belfast on June 25, 1824. His father, Dr. James Thomson, the son of a Scots-Irish farmer, showed a bent for scholarship when a boy, and became a pupil teacher in a small school near Ballynahinch, in County Down. The first clear message was sent through the cable on 13 Aug., and it continued working till 20 Oct., during which period 732 messages passed through the cable, and then it finally broke down ; probably the insulation had given way owing to the excessively strong currents used at first in working it. The joints were carefully made in the pipes, and they were smoothed inside to prevent any possible abrading of the cable. The system is constructed as follows: Eight wrought-iron pipes, three inches in diameter, are laid side by side in two rows, about four feet below the surface.

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. He remained chief engineer of the Magnetic company until 1860, and consulting engineer till 1870. During this period he took out several important patents, what is electric cable one in October 1852 (No. 14331 of 1852) for 'improvements in making telegraphic communications and in instruments and apparatus employed therein and connected therewith.' In this patent is to be found the first mention of sets of resistance coils constructed so as to form a series of different values. It may be argued that these were more interesting sets than the Northern and Western Electric's 302 and 354's of the same era.They were certainly a unique design. The cost of piping and chambers would be nearly as great for one hundred circuits as for one thousand, as the cost of chambers and the labor of excavating and filling would be the same; so that the cost for one hundred wires may be estimated at $50,000 per mile, or $500 per mile per conductor. The cost of one wire by itself is vastly larger than where many are run together, the cost of the pipe and for laying being not much greater for fifty wires than for one, and the cost of single wire cables being greater per mile of wire than multiple wire cables, so that the expense of putting such a system as one of our telephone exchanges entirely under-ground would place the cost of the instruments entirely out of reach of the subscribers.

The cables, of which several kinds are in use, run out from the basement of the central office through these pipes and up the side of buildings to roofs, from which they spread out to the subscribers by means of ordinary overhead lines. In both instruments the signals are sent by means of a perforated ribbon of paper; but the cable sender was the more complicated, because the cable signals are formed by both positive and negative currents, and not merely by a single current, whether positive or negative. The present European system dates from 1875. The cable is similar to that used for submarine purposes. Such a system would be more durable, needing fewer repairs, than the present, and would not be much more expensive. This prohibits further extension of the single-wire system under-ground, for technical reasons. If a subscriber in one city wishes to talk with a subscriber in a neighboring city, both cities must have metallic-circuit systems and metallic circuits between the two cities. In almost all of the large cities the question is now being asked, Why can not all of these wires be buried along with the gas and water pipes under the streets? India-rubber had been tried by Jacobi, the Russian electrician, as far back as 1811. He laid a wire insulated with rubber across the Neva at St. Petersburg, and succeeded in firing a mine by an electric spark sent through it; but india-rubber, although it is now used to a considerable extent, was not easy to manipulate in those days.