Publication: The Telegraphic Journal and Electrical Review
THE TELEGRAPH IN THE DESERT.
By K. JOYCE PERCEVAL.
I AM not going to write about any political or financial affairs, but simply confine myself to the part I took, as well as what I saw, during the erection of the telegraph to India through Mesopotamia, in Turkish Arabia, in 1863-4-5.
After the failure of the Red Sea cable between Suez and Aden became an established fact, the British Government obtained the sanction of the Sultan of Turkey to erect a land line from Bagdad to Bussarah, and a loop line from the former city to Kermanshah, where it joined the main line between Teheran and the port of Bushire in the Persian Gulf. The line to Bussarah, which runs between the Rivers Tigris and Euphrates, via Babylon and Hillah, is in the Turkish territory; but there are only 112 miles of the Kermanshah loop under the jurisdiction of the Turkish authorities, which extends 3 miles beyond the ancient town of Khanakcan, and within 14 miles of the historic village of Kasr-Sherin, the first Persian place of permanent habitation on the Bagdad route to Teheran and Kermanshah. England paid for the cable and the materials for the land lines, and laid and erected both at her own expense.
It was to aid in the erection of the land lines that my services were engaged by the Under-Secretary of State for India.
The cable being finished, and the materials for the land lines shipped to the ports of destination, Bussarah and Bushire, I received orders from the Government (after having undergone a course of practical instruction at the telegraphic factories of Messrs. Siemens and Henley) to proceed to Bagdad, via Alexandria, Beyrout, Damascus, Palmyra, the Syrian Desert, and Kubisa.
Before my arrival most of the materials for the erection of the land lines were landed at Bagdad, and some portion was distributed along the intended direction which the lines were supposed to take. Every telegraph line is either suspended above ground by means of insulators fastened to wooden or iron posts, or laid underground, when the wire is protected by a covering of gutta-percha, and generally passed through iron or wooden tubes, such as can be seen daily in the streets of London. The lines I am now going to describe were all above ground, and the posts used were of cast- and wrought-iron, and manufactured by Siemens Brothers, of Great George Street, Westminster. Each post consists of a buckled foot-plate of wrought-iron, which is fastened to a east-iron tube which forms the lower portion of the post. The top part is a wrought-iron welded tube combining great strength with lightness, and is fastened in the socket or lower portion of the post during erection by means of cement and small iron wedges, or by the conical end of the upper tube fitting tightly into the socket. A lightning discharger, commonly called a conductor, an iron rod 18 inches high and 1/2 an inch in diameter, is fastened into the top of the upper tube for the purpose of discharging atmospheric electricity. The insulators which I used, manufactured also by Siemens Brothers, were of porcelain, strengthened and protected by iron. I consider these to be the best materials of the many that have been patented or recommended. The insulators, which are divided into two classes, although used on the same line, are styled "intermediate" and "straining" insulators. Cost as follows:—Intermediate post insulators, according to size and quality, complete, from is. 3d. to 2s. each; straining or stretching insulators, complete as above, from 3s. 3d. to 4s. 6d. each. The iron parts of the insulators are painted with black varnish or galvanised. The number of insulators and posts required per mile varies according to the nature of the ground selected for the line. I used on an average, when on level ground, eighteen intermediate and three straining poets to every mile; hut on other occasions, where the ground was rocky or hilly, I used twenty-four and twenty-six posts, which gave a span of 73 yards 1 foot between the posts, whereas those erected on the level had a span of 83 yards 2 feet 5-1/2 inches; but often in crossing from one cliff to another the spans were 150 and 200 yards. On these occasions I used Siemens Brothers' steel wire and elevated my posts, which can easily be done by putting several wrought-iron tops of intermediate posts on the top of the straining-posts, which I buried 5 or 6 feet in the ground. When the ground is level the strain on the intermediate insulators is nominal, unless there is too much dip or slack allowed between each post, which should never exceed in warm countries more than 18 inches to every 84 yards. I may add that curves never work so well as straight lines of telegraph, with more wear and tear of material, and larger original cost for erection.
The insulators are porcelain inverted cups, firmly cemented in a metallic covering, bell-shaped, cast-iron. A wrought-iron stalk is also cemented inside the porcelain cup, which has a hook on the end to support and retain the wire, which allows it to slide in the supporting hook when the temperature either expands or contracts the wire. The cast-iron bell protects the porcelain cup from injuries, and also from wet, which is essential in regard to insulation. The insulators are not liable—as glass, or some kinds of ebonite—to decrease in insulation after being exposed for some time to the weather; glass, owing to a chemical change of its surface, and ebonite, owing to numberless fine fissures which appear frequently on its surface, and absorb the humidity of the atmosphere.
Wooden posts, even in dry countries, seldom last more than five or six years before they must be replaced by new ones, without speaking of the expense incurred in putting them upright after every winter. I must say that the durability of wooden posts may be increased to some extent by the injection of sulphate of copper into the fibre of the wood; but that must be done just after the wood is cut down, or the expense incurred by the process is like throwing so much money away.
The iron posts patented by Siemens Brothers, and sent to me for erection, had been constructed with a view to obtain the greatest possible strength and durability with the least possible weight, and give each of the principal pieces composing the poles convenient shape for easy transport. The cost of each post and insulator complete is indeed very moderate if we only take into consideration that it will last, with proper care, between seventy and eighty years. The wrought iron buckle-plate, already mentioned, gives to the pole stability and resistance against movement, and being round and gradually tapering upwards it presents but a very small surface to the wind and weather, whereas the clumsy, heavy, wooden post has no basis under ground to maintain it in its proper position; and even if it is plugged with heavy stones all round, the surface it presents to the wintry winds and rains will displace it, unless protected by a strong and costly ring of stays. There is another advantage to be gained by the iron post and foot-plate:—the post need not be sunk