Ancient American and Indian Electric Searchlight Technology
Ancient American electric searchlight technology and other incandescent lighting progressed throughout the latter half of the nineteenth century; but technology in electric searchlights had originated in ancient India and elsewhere. In this excerpt from “Electricity in Naval Warfare,” an article in the October, 1889 issue of Schribner’s Magazine, U. S. Navy Lieutenant W. S. Hughes updates us on some of the current details of the naval progress in electric searchlights, which was widely displayed four years later at Chicago’s World Fair:
“The extension of the applications of electricity has been nowhere more rapid or remarkable than on board ships-of-war. Only a little more than six years have elapsed since the Navy Department fitted out the frigate Trenton, with an electric incandescent plant, and, so far as is known, she was the first naval vessel to be lighted by electricity.
[Note, electric “incandescent” lighting used in this article means “filament” lighting. However, “incandescent” electric lighting to mean Edison type filament lighting only is a gross misnomer that has persisted over the past two centuries. The time has come to correct the error. Anything that glows or produces light by heat is incandescent. Electric carbon arc and filament lights are just two examples of incandescent lighting. Too many writers are sloppy and repeat errors, and this causes misnomers like this to persist.]
“The experiment with the Trenton was watched with interest both at home and abroad. Serious apprehensions had been entertained that firing the ship’s guns would break the glass bulbs, or destroy the carbon filaments of the lamps, and that other causes would operate against the successful employment of electricity on board a man-of-war; but the thorough test on the Trenton, lasting through a three-years’ cruise, proved beyond question the fallacy of such fears.
“Foreign countries were not slow to follow the footsteps of the United States, and the latter government gradually extended the system of electric lighting to other vessels of the navy.
“It had been early discovered that the installation of an electric plant on board naval ships required a decided modification of the electrical appliances employed for similar purpose on shore.
The limited space that could be spared on the crowded decks of a man-of-war demanded that engines and dynamos of a special and compact type should be used; and these requirements were further complicated by the necessity, which soon developed, of providing naval vessels with two systems of illumination. . . . At the present day, no modern-built vessel-of-war goes to sea without complete electrical plants, both ‘arc’ and ‘incandescent,’ the latter principally for the purpose of interior lighting, and the former for operating the so-called ‘search-light.’
“The name of the ‘search-light’ suggests, to some extent, the chief purpose for which it is used. It is mainly employed in searching for an enemy. It consists of a powerful ‘arc’ light usually of about twenty-five thousand candle-power, contained in a metal cylinder about thirty inches long by twenty-four to thirty inches diameter. A good idea of the construction and general appearance may be obtained form the illustration above and the next one.
“One end of the cylinder is closed by a silvered concave, reflecting lens; and the carbon points of the lamp, as represented in the sectional view, are placed in such position within the cylinder as to bring them in the focus of the lens. The opposite, or front, end of the cylinder is fitted with a glass door through which the beam of light passes. Other mechanical features are shown in the illustrations.
“The whole apparatus is mounted on a pivot, so that it may be revolved around its center—and the beam of light be thus thrown in any desired direction—while it admits, also, of elevation or depression from a horizontal position.
“As ordinarily used on ships-of-war, the beam of light emerging from the cylinder is so concentrated that at a distance of a thousand yards from the ship it illuminates a patch only about fifteen yards in width. Every search-light, however, is provided with arrangements for increasing the divergence of the rays of light, in order, when necessary, to illuminate a broader arc. Only one man is required to operate the apparatus, and to facilitate its use it is always, on board ships, mounted in some position considerably elevated above the deck.
“In time of war, ships at night would constantly sweep the surrounding waters with their search-lights, illuminating in succession, every part of the circle around them, in order to detect the presence of an enemy; and the practical value of the light in such cases, will be readily comprehended when it is understood that, with one of only twenty-thousand candle-power, no difficulty is experienced in lighting up an object such as an enemy’s ship, at a distance of two and a half miles; thus rendering firing the guns at night as easy and accurate as by day.
“The view at the beginning of this article of the Empong, one of those phenomenally swift little vessels called ‘torpedo-boats,’ shows its search-light mounted on top of the pilot-tower, just in front of the two smoke pipes.
“In the practical use of the search-light, by the method just explained, it has been found that in order to afford sufficient time for a careful examination of the water’s surface at points far removed from the ship, the beam of light must be revolved very slowly; and, in consequence, during a great proportion of the time, any particular section of the water is in darkness. When it is remembered that it requires less than five minutes for modern torpedo-boats to pass over a distance of two miles, it may be easily conceived how, in the interval between two successive illuminations of the same spot, a little craft like the Empong might dart in and discharge its torpedoes.
“With the object of averting such a danger, another method of illuminating the surrounding space has been adopted on one or two ships of the French Navy, and on the Danish cruiser Ivert, where, instead of a single revolving light, a number of stationary searchlights are grouped together, and each illuminating its proper section, thus keeping the ship continuously surrounded by an unbroken circle of light.
“But the searchlight is not only used to discover the enemy, and to keep the latter visible in firing at night; it has been, also, successfully employed in signaling messages where the distances over which they be sent are very great One of the methods of using it for this purpose is somewhat novel; the beam of light is simply flashed repeatedly against the clouds, lighting them up in each instance for a certain number of seconds, according to a pre-arranged code of signals, the letters of which are indicated by combinations of flashes of different durations of time. Messages are said to have bee sent in this manner between ships separated by a distance of sixty miles.”
Messages were also flashed out with an electric carbon arc searchlight from the ancient lighthouse at Alexandria, Egypt in the third century B. C.
However, ancient electricity and electric searchlight technology were apparently utilized in ancient India long before then. Several Sanskrit verses of the Atharvaveda, originating about 1,000 B.C., allude to electricity, electric wires, and electric power—and even the searchlight utilizing them. At other times, the verses simply spell out these words. The following excerpts that clearly spell them out are taken from Kanda (Book) XX of Devi Chand’s translation of this ancient magical (or technical) work:
“O well-versed engineer make use of this terrible electric power fit to be utilized for useful purposes by controlling it, for non-violent, brilliant light like the dawn [light like an electric arc light]. It has the potentiality to help hearing, control energy, and spread light in all quarters. (Hymn XV—3)
“O powerful electric power [from an electric mirror], thou revealest over the distant sea or the high up atmospheric ocean. Even in the projects, built by us, thou shouldest freely run into currents. (Hymn CXI—2)
“O current electricity of high voltage, safely carried by electric wires, you kill many enemies in the war, waged by learned persons or through the help of natural forces. (Hymn XXXVII—4)”
And (Hymn XLV—3) even plainly states: “Let this Anjana, which is got from the mountains, which creates four-fold energy i.e., hydraulic power, enhancement of splendor, born of heat, predominating light, like the searchlight, make all the quarters and the mid-quarters peaceful for thee (man or king).”
For much more, see The Electric Mirror on the Pharos Lighthouse and Other Ancient Lighting.
This page was last modified on Wednesday, August 18, 2010