Lamp Inventors 1880-1940:
From The Illuminating Engineer, June-July 1906
by the Moore Electrical Company.
D. McFarlan Moore, 1906
photo taken by the light of a Moore Lamp
"It's too small, too hot, and too red."
McFarlan Moore, speaking to Thomas Edison, 1898
Daniel McFarlan Moore is little remembered today. However, he invented one of the
first commercially available discharge lamps as well as a small glow lamp that can still be
found in almost every American home.
Moore began his lighting career working for Edison, but turned to
experimenting with the idea of obtaining light from electrical discharges. While not a new idea -- Henrich Geissler made light emitting tubes in the 1850s -- Moore felt that glass sealing techniques had advanced enough since then to allow a commercial product.
Edison was not keen on the idea of something which might compete with his incandescent lamp, and reputedly asked Moore, "What's wrong with my lamp?" Moore's quick response, quoted above, should leave little wonder why Moore soon started into business for himself.
By 1898 Moore had devised his "Moore Lamp." The lamp
consisted of gas-filled glass tubes about 2 inches in diameter
joined together in lengths up to 250 feet. Once installed, air was removed from the tube and a small amount of gas, usually nitrogen or carbon dioxide,
inserted. An electric current passed between electrodes mounted in either end of the
lamp, just as in later neon tubes inspired by Moore's work. Current and gas pressure were
regulated by devices installed in a box from which both ends of the tube emerged.
The Moore lamp proved difficult to install, requiring the services of a "glass
plumber" who custom fit 10 foot lengths of tubing to a customer's space. The tubes also
leaked. But carbon dioxide gave a good quality white light at an efficacy of about 10
lumens per watt -- almost triple the efficacy of Edison's lamp. Moore lamps sold modestly well for commercial installations, until 1910 when William Coolidge's tungsten filament lamp also achieved 10 lpw. Moore's company failed and he went to work for General Electric.
Moore's lasting legacy was his 1920 invention of the glow lamp. These small, low
power devices use a physical principle called "coronal discharge." Moore mounted two
electrodes close together in a bulb and added neon or argon gas. The electrodes would glow
brightly in red or blue, depending on the gas, and the lamps lasted for years. Since the electrodes could take almost any shape imaginable, a popular application has been fanciful decorative lamps. Glow lamps found practical use as indicators in instrument panels and in many home appliances until the acceptance of Light-Emitting Diodes
(LEDs) in the 1970s. The next time you see a coffee urn with an orange, glowing light above the spigot, think of D. McFarlan Moore.