Arc Lamp - History - Carbon-arc Lighting in The U.S.

Carbon-arc Lighting in The U.S.

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 Faraday's dynamo. The concept was improved upon by a number of people including William 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 in Cleveland, Ohio, on April 29, 1879. In 1880, Brush established the 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 filament lamps.

The usage of Brush electric arc lights spread quickly. Scientific American reported in 1881 that the system was being used in:

• 800 lights in rolling mills, steel works, shops, etc.
• 1,240 lights in woolen, cotton, linen, silk, and other factories
• 425 lights in large stores, hotels, churches, etc.
• 250 lights in parks, docks, and summer resorts
• 275 lights in railroad depots and shops
• 130 lights in mines, smelting works, etc.
• 380 lights in factories and establishments of various kinds
• 1,500 lights in lighting stations, for city lighting, etc.
• 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:

• 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.
• František Křižík invented a mechanism to allow the automatic adjustment of the electrodes.

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 Company 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. Nikola Tesla received U.S. Patent 447920, "Method of Operating Arc-Lamps" (March 10, 1891), that describes a 10,000 cycles per second alternator to suppress the disagreeable sound of power-frequency harmonics produced by arc lamps operating on frequencies within the range of human hearing.

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 Company.

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. 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. In the 1920s, carbon arc lamps were sold as family health products, a substitute for natural sunlight.

Arc lamps were superseded by filament lamps in most roles, remaining in only certain niche applications such as cinema projection, followspots, and searchlights. Even in these applications conventional carbon arc lamps are being pushed into obsolescence by xenon arc lamps.