History of the Atlantic Cable & Undersea Communications
from the first submarine cable of 1850 to the worldwide fiber optic network
Aber Geirch (Nevin), Wales - Newcastle, Ireland
A paper by Major W.A.J. O'Meara read on 15 December 1910 at a meeting of the Institution of Electrical Engineers in London gave these details of the 1898 Anglo-Irish telephone cable:
In 1895 Messrs. Willoughby Smith and W. P. Granville took out a patent for a type of submarine cable core which was designed to combine the advantages of an "air-space" cable with low capacity, and of gutta percha insulation with its well-known durability and impermeability to moisture. The method of building up the core will be obvious from the figure, which represents a section of the "air-space" cable laid in 1898 between Nevin, North Wales, and Newcastle, Co. Wicklow.
Each conductor consists of a central wire 5o mils in diameter surrounded by ten wires each of 22 mils diameter. Two conductors were covered with gutta percha so as to form a crescent-shaped semicircular segment, as shown in the Fig. Two such crescent-shaped strips were then "laid" together with a helical twist and doubly covered with gutta percha to a diameter of 0.58o in., forming a tubular core.
The weight per knot of each of the four conductors was 138 lbs., and the total weight of gutta percha 552 lbs. per knot, that is, equal to the total weight of copper. The conductor resistance was 8.515 ohms per knot at 75° F., and the wire-to-wire capacity of diagonal pairs 0.1016 microfarad per knot. This capacity is about 19 per cent. less than the mutual capacity of two conductors in the ordinary Post Office type of submarine telephone cable. To prevent flooding of the whole cable in case of damage at any point the core was made solid at the joints.
Copyright © 2008 FTL Design
30 September, 2008
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