CARBON ARC SEARCHLIGHTS
Larry Brian Radka's The Electric Mirror on the Pharos Lighthouse and Other Ancient Lighting covers a lot of lighthouse history that includes the use of carbon arc searchlights used in ancient light towers. And the Electric Mirror brings the history of carbon arc searchlights well into the recent era of strong light beams, with reports like the following:
The Sandy Hook proving ground, off the coast of New Jersey, may have seen a large carbon arc searchlight at one time before it closed in 1919. “A BIG SEARCHLIGHT—To be Mounted at Sandy Hook for Army Experiments” is the title of an interesting article published by The New York Times on December 31, 1893. The piece reads as follows:
“One of the biggest electric searchlights in the world is to be mounted at Sandy Hook. Gen. Flagier, the army Chief of Ordinance, will purchase a monster light for experimental purposes. The apparatus desired, including the light proper, the dynamo, the steam engine and boiler, will cost between $6,000 and $10,000.
“The workings of the big electric searchlight at Chicago on the roof of the Liberal Arts Building suggested that experiments with another large light would be valuable. It is likely that the German firm which constructed the Chicago light will make the light for Sandy Hook. The bid of that company was $5,900, while the next lower bid was that of the General Electric Light Company of this city, $11,500 in amount. The searchlight has by its use on shipboard become an important part of torpedo warfare. It is absolutely necessary in the operations at night, and the more powerful the light the less will the attacking party be able to do.
“Gen. Flagier believes that the searchlight will be very useful in the coast-defense forts at the large ports, and it is with the view of ascertaining utility of these lights that the present apparatus is to be bought and experiments conducted at Sandy Hook proving ground. The system comprises the light proper, with mirror about 60 inches in diameter, furnished with a horizontal arc lamp. The mechanism must be capable of giving the light a rotation in a horizontal and vertical plane, and a governor must be provided to permit of electrically training the apparatus from a distance. The dynamo must produce an intensity of light of about 200,000,000 candle power, while the energy consumed in the lamp must not exceed 150 amperes by 60 volts. The makers of the light must keep it in operation for eight successive nights at Sandy Hook before it is accepted by the Government, and must instruct the force of operators who are chosen by the Ordinance Office.”
The New York Times' Sandy Hook article above may have encouraged a carbon arc light to be placed at a later date in the south tower (shown directly above) of the Twin Lighthouses at Navesink, New Jersey (also shown above it). The dazzling light produced a 250,000,000 candle- power carbon arc blaze that could be seen 22 nautical miles away. Some of its rays cleared the curvature of the earth and bounced off the clouds in the distant night sky some seventy nautical miles away.
Although Larry Brian Radka did not say much about the Navesink Lighthouses in The Electric Mirror on the Pharos and Other Ancient Lighting, his continuous research allowed him to discover more after he had his work printed. So he will include this additional information here. Yet, the history of the Navesink lighthouse's carbon arc light located on the New Jersey highlands is not, however, perfectly clear:
At some time in 1896, a huge electric carbon arc light apparatus and gigantic fresnel lens left New York's Fire Island Lighthouse and eventually arrived on December 21st at the U. S. Lighthouse Depot at Tompkins-ville on Staten Island for testing. Apparently, the arrange- ment remained there for over a year, before being installed in the south tower of the Navesink Light on New Jersey's highlands in June of 1898. At least, this is what the 1898 Report to Congress from the Lighthouse Board seems to indicate. "Although not authenticated, there is some opinion that the generator plant and the 2nd order bi-valve lens initially slated for Fire Island went to Navesink," wrote Editor Wayne C. Wheeler, in the summer 2000 edition of The Keeper's Log.
Nevertheless, Scientific American, dated January 29, 1898, included illustrations of the arc light, regulator, driving mechanism and its lens shown in its picture above; and this rare issue described the beacon as follows:
"A NINETY MILLION CANDLE POWER ELECTRIC BEACON
"A truly gigantic electric light beacon, shown in the accompanying illustrations, is just now being made the subject of a series of tests at the United States Lighthouse Depot, at Tompkinsville, Staten Island, N.Y. It was manufactured by Henri Lepaute, of Paris, and was first exhibited at the Chicago World’s Fair and subsequently at Atlanta and Nashville. It consists of two great lenses, each 9 feet in diameter, between which, in their focus, is placed a 9,000 candle power arc light. The valves and the light are carried by a vertical shaft which terminates at its lower end in a hollow drum, which latter floats in a bath of mercury. The great weight of the lantern, estimated at several tons, is thus carried by the mercury, and friction is reduced to such a point that the whole mass may easily be rotated by the pressure of one’s finger.
"Each lens consists of a set of lenses and prismatic segments, which are built up concentrically within a stout framework of brass, into which the segments are carefully cemented. The center of the lens consists of a solid disk. Surrounding this are eight concentric prisms, whose edges are in contact, and surrounding these are fourteen larger prisms, making 190 separate segments in the whole lens. The angles of the prisms are such that the rays of light are refracted so as to leave the lens in parallel non-divergent rays, and it is estimated that the 9-foot beam of light thus projected is of 90,000,000 candle power. The lantern is rotated by means of the clockwork which will be noticed at the right hand side of the framework. As there are two beams of light and the period of rotation is 10 seconds, every part of the horizon receives a flash once in 5 seconds, the duration of the flash being about one-twelfth of a second.
"The illumninant is an arc lamp of 9,000 candle power, which is so constructed that the arc will always remain in the exact focus of the lenses, the latter being so placed that their foci coincide. The maintenance of the arc in a fixed position is secured by connecting the carbon holders so that they both travel simultaneously and at the same speed, as the carbon points are burnt away. The carbons are fed together by the clockwork enclosed in the base of the lamp. The mechanism is controlled by an electromagnet arranged in shunt around the arc. As the carbons are burnt away the resistance of the arc increases and the magnet releases the clockwork escapement, permitting it to bring the carbons together. The feed is slow and frequent, maintaining the arc at a practically uniform length.
"The carbons vary in size from ⅝ to 2 inches diameter, and the 55-volt current will vary from 25 to 100 amperes, according to the carbons used. The current will be furnished by an alternating generator made by the General Electric Company, driven by a 25 horse power Ideal engine, steam being supplied by a 25 horse power Fitzgibbon’s boiler. When the lens is installed at a station the steam and electric plant will be furnished in duplicate, so that, should one set be disabled, the other can be brought at once into use.
"As a precaution against the extinction of the light through the failure of the lamp, the whole lamp with its mechanism is provided in duplicate, the two lamps being carried at each side of a turntable, which is a permanent fixture within the bivalve lens. The turntable is placed to the left of the common focus of the lenses in such a position that on rotating it either of the lamps may be brought at will into the focus. The lamps are carried on a sliding rest on the turntable, and by means of an endless screw operated by a handwheel on the outside of the lenses they may be drawn out for inspection or repairs.
"The theoretical luminous range of this giant lens in clear weather is 146.9 nautical miles ; and if the light were placed on a sufficiently lofty eminence to compensate for the curvature of the earth, it would be possible, under favorable circumstances, to see it at this distance. The geographical range, as it is called, depends on the height of the focal plane above the sea level. If the light were to be installed at Barnegat, where the height of the focal plane is 165 feet, the light would be visible from a vessel’s deck at a height of say 15 feet above the water at a distance of 19 nautical miles in clear weather, and, on account of its great power, at the same distance in hazy weather.
"In a dense fog, however, even such a great light as this would be practically extinguished. In this latitude the light may be expected to be seen to the limit of the geographical range for 330 nights out of the year.
"The present tests are being carried out by Lieut. Col. D. P. Heap, Corps of Engineers, U. S. A., engineer of the Third Lighthouse District, to whom we are indebted for particulars and photographs used in the preparation of the present article."
Although this article does not cover a normal carbon arc searchlight that has a mirror but a carbon arc light with a lens instead, The Electric Mirror on the Pharos Lighthouse and Other Ancient Lighting presents several examples of them anyway. For example, Chap. 2 of The Electric Mirror covers the three true carbon arc searchlights and their beams in the German lighthouse at Helgoland, and a picture of them is repeated near the top of this page.
Although Larry Brian Radka did not say much about the Navesink Lighthouses in The Electric Mirror on the Pharos and Other Ancient Lighting, his continuous research allowed him to discover more after he had his work printed. So he will include this additional information here. Yet, the history of the Navesink lighthouse's carbon arc light located on the New Jersey highlands is not, however, perfectly clear:
At some time in 1896, a huge electric carbon arc light apparatus and gigantic fresnel lens left New York's Fire Island Lighthouse and eventually arrived on December 21st at the U. S. Lighthouse Depot at Tompkins-ville on Staten Island for testing. Apparently, the arrange- ment remained there for over a year, before being installed in the south tower of the Navesink Light on New Jersey's highlands in June of 1898. At least, this is what the 1898 Report to Congress from the Lighthouse Board seems to indicate. "Although not authenticated, there is some opinion that the generator plant and the 2nd order bi-valve lens initially slated for Fire Island went to Navesink," wrote Editor Wayne C. Wheeler, in the summer 2000 edition of The Keeper's Log.
Nevertheless, Scientific American, dated January 29, 1898, included illustrations of the arc light, regulator, driving mechanism and its lens shown in its picture above; and this rare issue described the beacon as follows:
"A NINETY MILLION CANDLE POWER ELECTRIC BEACON
"A truly gigantic electric light beacon, shown in the accompanying illustrations, is just now being made the subject of a series of tests at the United States Lighthouse Depot, at Tompkinsville, Staten Island, N.Y. It was manufactured by Henri Lepaute, of Paris, and was first exhibited at the Chicago World’s Fair and subsequently at Atlanta and Nashville. It consists of two great lenses, each 9 feet in diameter, between which, in their focus, is placed a 9,000 candle power arc light. The valves and the light are carried by a vertical shaft which terminates at its lower end in a hollow drum, which latter floats in a bath of mercury. The great weight of the lantern, estimated at several tons, is thus carried by the mercury, and friction is reduced to such a point that the whole mass may easily be rotated by the pressure of one’s finger.
"Each lens consists of a set of lenses and prismatic segments, which are built up concentrically within a stout framework of brass, into which the segments are carefully cemented. The center of the lens consists of a solid disk. Surrounding this are eight concentric prisms, whose edges are in contact, and surrounding these are fourteen larger prisms, making 190 separate segments in the whole lens. The angles of the prisms are such that the rays of light are refracted so as to leave the lens in parallel non-divergent rays, and it is estimated that the 9-foot beam of light thus projected is of 90,000,000 candle power. The lantern is rotated by means of the clockwork which will be noticed at the right hand side of the framework. As there are two beams of light and the period of rotation is 10 seconds, every part of the horizon receives a flash once in 5 seconds, the duration of the flash being about one-twelfth of a second.
"The illumninant is an arc lamp of 9,000 candle power, which is so constructed that the arc will always remain in the exact focus of the lenses, the latter being so placed that their foci coincide. The maintenance of the arc in a fixed position is secured by connecting the carbon holders so that they both travel simultaneously and at the same speed, as the carbon points are burnt away. The carbons are fed together by the clockwork enclosed in the base of the lamp. The mechanism is controlled by an electromagnet arranged in shunt around the arc. As the carbons are burnt away the resistance of the arc increases and the magnet releases the clockwork escapement, permitting it to bring the carbons together. The feed is slow and frequent, maintaining the arc at a practically uniform length.
"The carbons vary in size from ⅝ to 2 inches diameter, and the 55-volt current will vary from 25 to 100 amperes, according to the carbons used. The current will be furnished by an alternating generator made by the General Electric Company, driven by a 25 horse power Ideal engine, steam being supplied by a 25 horse power Fitzgibbon’s boiler. When the lens is installed at a station the steam and electric plant will be furnished in duplicate, so that, should one set be disabled, the other can be brought at once into use.
"As a precaution against the extinction of the light through the failure of the lamp, the whole lamp with its mechanism is provided in duplicate, the two lamps being carried at each side of a turntable, which is a permanent fixture within the bivalve lens. The turntable is placed to the left of the common focus of the lenses in such a position that on rotating it either of the lamps may be brought at will into the focus. The lamps are carried on a sliding rest on the turntable, and by means of an endless screw operated by a handwheel on the outside of the lenses they may be drawn out for inspection or repairs.
"The theoretical luminous range of this giant lens in clear weather is 146.9 nautical miles ; and if the light were placed on a sufficiently lofty eminence to compensate for the curvature of the earth, it would be possible, under favorable circumstances, to see it at this distance. The geographical range, as it is called, depends on the height of the focal plane above the sea level. If the light were to be installed at Barnegat, where the height of the focal plane is 165 feet, the light would be visible from a vessel’s deck at a height of say 15 feet above the water at a distance of 19 nautical miles in clear weather, and, on account of its great power, at the same distance in hazy weather.
"In a dense fog, however, even such a great light as this would be practically extinguished. In this latitude the light may be expected to be seen to the limit of the geographical range for 330 nights out of the year.
"The present tests are being carried out by Lieut. Col. D. P. Heap, Corps of Engineers, U. S. A., engineer of the Third Lighthouse District, to whom we are indebted for particulars and photographs used in the preparation of the present article."
Although this article does not cover a normal carbon arc searchlight that has a mirror but a carbon arc light with a lens instead, The Electric Mirror on the Pharos Lighthouse and Other Ancient Lighting presents several examples of them anyway. For example, Chap. 2 of The Electric Mirror covers the three true carbon arc searchlights and their beams in the German lighthouse at Helgoland, and a picture of them is repeated near the top of this page.
