Lodge, Signalling across Space without Wires (3rd ed.
Between 1858 and 1868 he was employed in home waters on a variety of special services, chiefly connected with gunnery, signalling and the tactical characteristics and capacities of steam warships.
Among the subjects to which he especially directed his attention were the explosive force of gunpowder, the construction of firearms, and a system of signalling at sea.
It possesses depots for artillery and mines, a meteorological observatory and a signalling station.
If the positive is called the signalling current, the line will be charged positively each time a signal is sent; but as soon as the signal is completed a negative charge is communicated FIG.
Theoretically for a given outside diameter of core the greatest speed of signalling through a cable is obtained when the diameter of the conductor is 606 (1/,/e) the diameter of the core, but this ratio makes the thickness of the guttapercha covering insufficient for mechanical strength.
In this manner Trowbridge showed that signalling might be carried on over considerable distances by electric conduction through the earth or water between places not metallically connected.
To stray " earth currents," and very good signalling was established between the mainland and the rock.
At each signalling station was erected an insulated metallic surface facing and near to the ordinary telegraph wires.
In the first place it increased the visibility of the signalling instrument; in the second place it brought that instrument into the position in which it could most readily catch the operator's eye; and finally it eliminated the effort involved in associating one piece of apparatus with another and in finding that other.
With the adoption of relays the signalling between the subscribers and the exchange became automatic, and, with the introduction of the principle of double and automatic supervision on the cord circuits, it became possible for the operators to tell at any instant the state of a connexion.
The large modern trunk exchanges are equipped with relays and lamps for signalling purposes.
A complete system of signalling by night and day on the Morse system is worked by the police.
The inspections made by the officers of the Board of Trade under this act are very complete: the permanent way, bridges, viaducts, tunnels and other works are carefully examined; all iron or steel girders are tested; stations, including platforms, stairways, waiting-rooms, &c., are inspected; and the signalling and " interlocking " are thoroughly overhauled.
In certain respects, on the other hand, America has gone further than the United Kingdom, especially in the matter of automatic signalling, and in the operating of points and signals by electrical power or air-pressure instead of manual labour.
Again, if the speed is low and the trains infrequent, the signalling arrangements may be of a very simple and inexpensive kind, or even dispensed with altogether.
The Peak lies immediately to the south-west of the capital, in the extreme north-west corner of the island, and is used as a station for signalling the approach of vessels.
Services; the balloon establishment; the detention barracks; fire brigade stations; five churches; recreation grounds for officers and men; schools; and especially the military technical schools of army cooking, gymnastics, signalling, ballooning and of mounted infantry, Army Service Corps, Royal Army Medical Corps and veterinary duties.
Many novelties, too, such as the field telegraph, balloons and signalling, were employed.
Telephones had broken down; the mist prevented signalling, and despatch riders do not seem to have been employed.
In 1907 there were three general divisions of these schools: the Army School of the Line, for officers (not below the grade of captain) of the regular army and for militia officers recommended by the governors of their respective states or territories, offering courses in military art, engineering, law and languages; the Army Signal School, also open to regular and militia officers, and having departments of field signalling, signal engineering, topography and languages; and the Army Staff College, in which the students are the highest graduates from the Army School of the Line, and the courses of instruction are included in the departments of military art, engineering, law, languages and care of troops.
Stokes, and which were published in the Proceedings of the Royal Society for 1855, that he discussed the mathematical theory of signalling through submarine cables, and enunciated the conclusion that in long cables the retardation due to capacity must render the speed of signalling inversely proportional to the square of the cable's length.
There are also here Lloyds' signalling station, coast-guard stations, and the terminus of a branch of the SouthEastern & Chatham railway.
In this the tongue of the relay is kept over to the spacing side by means of a current flowing in one direction, but on the depression of the signalling key the current is reversed, moving the relay tongue over to the marking side.
Lodge, Signalling through Space without Wires, 3rd ed., p. 73, 1899.
High) which contains a fine peal of bells and also serves as a signalling tower.