Editing Arc lamp (section)

=== Carbon-arc lighting in the U.S. ===
[[File:Arc Lamp Examples.jpg|thumb|right]]
In the United States, there were attempts to produce arc lamps commercially after 1850, but the lack of a constant electricity supply thwarted efforts.  Thus electrical engineers began focusing on the problem of improving [[Michael Faraday|Faraday's]] [[dynamo]]. The concept was improved upon by a number of people including {{Interlanguage link|William Edwards Staite|de|William Edwards Staite}} and [[Charles F. Brush]]. It was not until the 1870s that lamps such as the [[Yablochkov candle]] were more commonly seen. In 1877, the [[Franklin Institute]] conducted a comparative test of dynamo systems. The one developed by Brush performed best, and Brush immediately applied his improved dynamo to arc-lighting, an early application being [[Public Square, Cleveland|Public Square]] in [[Cleveland, Ohio]], on April 29, 1879.<ref>{{cite web|url=http://www.positivelycleveland.com/pdf/ClevPubArt08_f.pdf |title=Cleveland+ Public Art |access-date=2009-05-18 |year=2008 |format=brochure |publisher=[[Positively Cleveland]] |page=3 |url-status = dead|archive-url=https://web.archive.org/web/20080517020529/http://www.positivelycleveland.com/pdf/ClevPubArt08_f.pdf |archive-date=2008-05-17 }}</ref>  Despite this, [[Wabash, Indiana]] claims to be the first city ever to be lit with "Brush Lights". Four of these lights became active there on March 31, 1880.<ref>[https://www.roadsideamerica.com/tip/10495 Roadside America]</ref>  Wabash was a small enough city to be lit entirely by 4 lights, whereas the installation at Cleveland's Public Square only lit a portion of that larger city.<ref>[http://www.positivelycleveland.com/pdf/ClevPubArt08_f.pdf Brush Lights, Cleveland] {{Webarchive|url=https://web.archive.org/web/20080517020529/http://www.positivelycleveland.com/pdf/ClevPubArt08_f.pdf |date=2008-05-17 }}</ref> In 1880, Brush established the [[Brush Electrical Machines|Brush Electric Company]].

The harsh and brilliant light was found most suitable for public areas, such as Cleveland's Public Square, being around 200 times more powerful than contemporary [[Incandescent light bulb|filament lamps]].

The usage of Brush electric arc lights spread quickly.  ''[[Scientific American]]'' reported in 1881 that the system was being used in:<ref>{{Cite journal |title=The Brush Electric Light |date=April 2, 1881 |url=http://www.machine-history.com/Brush%20Electric%20Company |journal=[[Scientific American]] |volume=44 |issue=14 |url-status = dead|archive-url=https://web.archive.org/web/20110111040515/http://www.machine-history.com/Brush%20Electric%20Company |archive-date=January 11, 2011 }}; also Ohio Memory Collection [http://www.ohiomemory.org/cdm/compoundobject/collection/p267401coll36/id/19824/rec/2 cover reproduction] {{webarchive|url=https://web.archive.org/web/20160313001257/http://ohiomemory.org/cdm/compoundobject/collection/p267401coll36/id/19824/rec/2 |date=2016-03-13 }}</ref>
800 lights in rolling mills, steel works, shops, 1,240 lights in woolen, cotton, linen, silk, and other factories, 425 lights in large stores, hotels, churches, 250 lights in parks, docks, and summer resorts, 275 lights in railroad depots and shops, 130 lights in mines, smelting works, 380 lights in factories and establishments of various kinds, 1,500 lights in lighting stations, for city lighting, 1,200 lights in England and other foreign countries.
A total of over 6,000 lights which are actually sold.

There were three major advances in the 1880s: [[František Křižík]] invented in 1880 a mechanism to allow the automatic adjustment of the electrodes. The arcs were enclosed in a small tube to slow the carbon consumption (increasing the life span to around 100 hours). ''Flame arc lamps'' were introduced where the carbon rods had metal salts (usually magnesium, strontium, barium, or calcium fluorides) added to increase light output and produce different colours.

In the U.S., patent protection of arc-lighting systems and improved dynamos proved difficult and as a result the arc-lighting industry became highly competitive.  Brush's principal competition was from the team of [[Elihu Thomson]] and [[Edwin J. Houston]].  These two had formed the American Electric Corporation in 1880, but it was soon bought up by [[Charles A. Coffin]], moved to [[Lynn, Massachusetts]], and renamed the [[Thomson-Houston Electric Company]].  Thomson remained, though, the principal inventive genius behind the company patenting improvements to the lighting system. Under the leadership of Thomson-Houston's patent attorney, [[Frederick P. Fish]], the company protected its new patent rights.  Coffin's management also led the company towards an aggressive policy of buy-outs and mergers with competitors.  Both strategies reduced competition in the electrical lighting manufacturing industry.  By 1890, the Thomson-Houston company was the dominant electrical manufacturing company in the U.S.<ref name="Noble_6">[[David F. Noble]], ''America By Design: Science, Technology, and the Rise of Corporate Capitalism'' (New York: Oxford University Press, 1977), 6-10.</ref>  

Around the turn of the century arc-lighting systems were in decline, but Thomson-Houston controlled key patents to urban lighting systems. This control slowed the expansion of incandescent lighting systems being developed by [[Thomas Edison]]'s [[Edison General Electric Company]]. Conversely, Edison's control of direct current distribution and generating machinery patents blocked further expansion of Thomson-Houston. The roadblock to expansion was removed when the two companies merged in 1892 to form the [[General Electric|General Electric Company]].<ref name="Noble_6"/>

Arc lamps were used in some early motion-picture studios to illuminate interior shots. One problem was that they produce such a high level of [[ultra-violet]] light that many actors needed to wear [[sunglasses]] when off camera to relieve sore eyes resulting from the ultra-violet light.  The problem was solved by adding a sheet of ordinary window glass in front of the lamp, blocking the ultra-violet.  By the dawn of the "talkies", arc lamps had been replaced in film studios with other types of lights.<ref>H. Mario Raimondo-Souto''Motion Picture Photography: A History 1891-1960'', McFarland and Company, 2007 {{text|ISBN}} 0-7864-2784-0, pg. 84 </ref> In 1915, [[Elmer Ambrose Sperry]] began manufacturing his invention of a high-intensity carbon arc [[searchlight]]. These were used aboard warships of all navies during the 20th century for signaling and illuminating enemies.<ref>I. C. B. Dear and Peter Kemp, eds., "Sperry, Elmer Ambrose," ''The Oxford Companion to Ships and the Sea'', 2nd ed. (New York: Oxford University Press, 2006). {{ISBN|0-19-920568-X}}</ref>  In the 1920s, carbon arc lamps were sold as family health products, a substitute for natural sunlight.<ref>{{cite web|url=http://einhornpress.com/rays.aspx|title=Eveready Carbon Arc Sunshine Lamp Advertisements|publisher=The Einhorn Press|access-date=11 November 2008|url-status = live|archive-url=https://web.archive.org/web/20090601175558/http://einhornpress.com/rays.aspx|archive-date=1 June 2009}}</ref>

Arc lamps were superseded by filament lamps in most roles, remaining in only certain niche applications such as [[movie theater|cinema]] [[Movie projector|projection]], [[spotlight (theatre lighting)|spotlights]], and searchlights. In the 1950s and 1960s the high-power D.C. for the carbon-arc lamp of an outdoor drive-in projector would typically be supplied by a [[motor-generator]] combo (AC motor powering a DC generator). Even in these applications conventional carbon-arc lamps were mostly pushed into obsolescence by [[xenon arc lamp]]s, but were still being manufactured as spotlights at least as late as 1982<ref>{{cite web |url=http://www.film-tech.com/manuals/STRSTRONGHIST.pdf |title=Archived copy |website=www.film-tech.com |access-date=13 January 2022 |archive-url=https://web.archive.org/web/20010613202309/http://www.film-tech.com/manuals/STRSTRONGHIST.pdf |archive-date=13 June 2001 |url-status=dead}}</ref> and are still manufactured for at least one purpose – simulating sunlight in "accelerated aging" machines intended to estimate how fast a material is likely to be degraded by environmental exposure.<ref>{{Cite web|url=http://www.edisontechcenter.org/ArcLamps.html|title=Arc Lamps - How They Work & History|last=Center|first=Copyright 2015 Edison Tech|website=www.edisontechcenter.org|access-date=2018-01-13|url-status = live|archive-url=https://web.archive.org/web/20170617231552/http://www.edisontechcenter.org/ArcLamps.html|archive-date=2017-06-17}}</ref><ref>{{cite web|url=http://www.sca-shinyei.com/suga |title=Index of /suga |access-date=2015-04-16 |url-status = dead|archive-url=https://web.archive.org/web/20150427143242/http://www.sca-shinyei.com/suga |archive-date=2015-04-27 }}</ref>

Carbon arc lighting left its imprint on other film projection practices. The practice of shipping and projecting motion pictures on 2,000-foot reels, and employing "changeovers" between two projectors, was due to the carbon rods used in projector lamphouses having a lifespan of roughly 22 minutes (which corresponds to the amount of film in said reels when projected at 24 frames/second). The projectionist would watch the rod burn down by eye (though a peephole like a welder's glass) and replace the carbon rod when changing film reels. The two-projector changeover setup largely disappeared in the 1970s with the advent of xenon projector lamps, being replaced with [[Movie_projector#Single-reel_system|single-projector platter systems]], though films would continue to be shipped to cinemas on 2,000-foot reels.