1911 Encyclopædia Britannica/Tramway > 자유게시판

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Upward of 30,000 miles of cable have been laid since the report of the committee was printed, eleven years in the past, and much expertise has been gained of the exigencies incidental to submerging, buoying, grappling, and repairing; however no reality has resulted from all that experience which has established that anybody precaution really useful in the report has been superfluous, whereas a lot has occurred, which I can't particularize, proving that any try to disregard any single precaution has resulted in great pecuniary loss or utter failure. It consists of a really lengthy nice coil of silk-lined copper wire, and in the heart of the coil, within somewhat air-chamber, a small spherical mirror, having 4 tiny magnets cemented to its again, is hung, by a single fibre of floss silk no thicker than a spider's line. They had been accordingly changed by wires strung on poles, and the rest of the line was constructed in this fashion. The introduction of gutta-percha, in 1846, accordingly gave a brand new impetus to under-ground development, and, though it took years of experimenting and millions of dollars, and although system after system failed in England, Germany, and the remainder of Europe, there exists to-day a profitable and durable system of below-floor telegraph wires connecting collectively the principal cities of the German Empire, moreover many different beneath-floor lines in numerous components of Europe.

Hardly was the part completed, nevertheless, when water found its method into the joints, destroying the insulation, and the conductors failed. This line failed in exactly the identical way because the American traces, and the pipes have been dug up and placed on short posts six inches above the bottom. Within the Morse code the letters of the alphabet are represented by combinations of two distinct elementary signals, technically known as 'dots' and 'dashes,' from the truth that the Morse recorder really marks the message in long and short strains, or dots and dashes. The Red Sea cable, coated externally with mild wires, and unprotected with bituminous compound, was so rusted in a short while that it could not be lifted for repairs. Mr. Woodehouse, the engineer who laid this core, stated in his proof he "mustn't advise anybody to lay so light a cable across the Atlantic, as a result of so small a strain would break it. Whether it is once safe at the underside, maybe it could relaxation." Mr. Newall stated he thought it folly to put any thing excepting unprotected core. The very light cable invented by Mr. Varley (No. 21) admits of being laid by having the pressure taken off the core by the two hempen strands, the core itself being the third strand of the cable.

A mild cable or unprotected core should subsequently be regarded at greatest as an experiment, with the chances in opposition to the successful laying, and nonetheless extra against its current as a everlasting property. All cables which have been manufactured and laid upon the ideas which have been established in 1859 are yet in good working order, and every divergence from these principles has been at best but a pricey experiment or utter failure. 1. If an electric conductor be introduced near to a big mass of conducting matter, as is a wire when it is taken down from a pole and buried in the earth, there appears in the present the phenomenon of retardation, by which every sign, as a substitute of being sharp and distinct, is partly saved back, so that it overlaps and mingles with the following; the result's to limit the speed of working of the apparatus; or if, like the phone, or not it's an apparatus through which the currents are essentially extraordinarily frequent, to confuse and destroy the alerts altogether. With delicate relays, and extra particularly with quick working printing telegraphs, or automated telegraphs, such lines are very troublesome; and, with telephones, the retardation is a really troublesome matter on beneath-floor traces ten miles lengthy.

Between the years 1847 and 1850 a system of cables, containing 2,648 miles of wire, was laid underneath-floor to connect Berlin with the other principal cities of Prussia. Notwithstanding, Mr. Newall's partiality for mild cables, he suggests at the shut of his evidence what I assume he would consider probably the most excellent type of cable. I need to put in writing with nice respect for the opinions of the talented males who urge the adoption of mild cables; it's my special duty to weigh effectively and without prejudice all they need to advance; however I think a careful investigation into the experience and apply of the last twenty years establishes conclusively that each one gentle cables have been short-lived, and that each one heavy cables have continued working, often under most opposed conditions. Again, it is urged that experiments with mild cables have been tried in factories or sheds, and the outcome proves that there are a lot of advantages of their favor; however I am of opinion that no experiments which may be made on shore will sufficiently resemble the exigencies which can happen over a interval of a number of days and nights at sea in storms and darkness, and nonetheless much less will they show their health for the unknown conditions which can exist at nice ocean-depths.