The electric flash-lamp is a device that uses an electrical circuit to trigger a fuse to ignite explosive powder (e.g., magnesium) for a brief sudden burst of bright light ("flash") from a chemical reaction of flash powder burning.[1] It was principally used for flash photography in the early 20th century, but had other uses as well.
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The flash-lamp was invented by Joshua Cohen (a.k.a. Joshua Lionel Cowen of the Lionel toy train fame) in 1899. It was granted U.S. patent number 636,492.[2] This "flash" of bright light from the flash-lamp was used for indoor photography in the late nineteenth century and the early part of the twentieth century.[1]
Joshua Lionel Cowen's flash-lamp patent 636,492 reads in part,
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My appliance comprises a tubular casing A, to be held in the hand, an upright detachable post B, and a horizontal through part C to receive the flash-light powder. The casing A is adapted to contain cells of dry battery, which can be introduced into or removed from the lower end through an opening closed by the sheet-metal screw-cap c. The walls of the casing may be of metal and covered with leather or imitation leather or any other suitable material. At the upper end one pole of the uppermost cell will be in contact with the insulated pin a', Fig. 2, while opposite the opposing pole of the lowermost cell lies a push-button contact D, on pressing which the circuit can be closed at that point to the metal casing.[2] |
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The principle of operation of the electrical flash-lamp is linked to the shutter of an early box camera: tripping the shutter ignites the flash powder and releases the potential energy of the exploding powder causing a bright flash for indoor photography.
The main purpose of Cowen's invention was as a fuse to ignite explosive powder to get a photographer's flash.[3] One of the first practical applications, however, for Cowen's flash-lamp was as underwater mine detonator fuses for the U.S. Navy.[4][5][6][7][8][9] In 1899, the year the invention was patented, the government awarded Cowen a $12,000 contract for 24,000[10] naval mine detonator fuses.[11]
A 1910 brochure for the Nesbit High Speed Flashlight Apparatus says,
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"Raise up the movable plunger and spread the powder also over the bottom of the plunger chamber, under the head of plunger. Insert the electronic squib well into the hole for same, as shown by Fig. 7. Set up the camera and focus upon the object to be photographed. Set the flash outfit a little behind and the right side of the camera. Connect the plunger H by the wire G to the shutter prop in place under the shutter lever, so placing any wire directing screw eyes that the prop will be pulled away from the camera in such a direction as to not shake same. Set shutter at the desired speed, pull out slide, attach firing line to fuse leads, and insert plug on end of firing line into receptacle in end of battery carrying case. This connection should be made last to minimize danger of accidental discharge. A push on the button of the switch will now fire the powder."[12] |
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On 10 January 1899 American Electrical Novelty and Manufacturing Company obtained U.S. Patent No. 617,592 (filed 12 March 1898) from a David Misell, an employee of Cowen.[13] This "electric device" designed by Misell was powered by "D" batteries laid front-to-back in a paper tube with the light bulb and a rough brass reflector at the end.[14] Misell, an inventor, had previously invented a portable electric lamp in 1895 as patent number 551,394.[15] He also invented a bicycle head lamp in 1896 as patent number 559,143.[15]
Since early flashlights used energy-inefficient carbon filament bulbs, the batteries ran down quickly, and consequently they could only be used for brief flashes of light, hence the popular American and Canadian term flashlight.[16]