Edison's Electric Light: The Art of Invention

Who Invented the Incandescent Lamp?

The Triumph of Carbon 91 Who Invented the Incandescent Lamp? Edison was neither the only nor the first inventor to try to make an incandescent electric light.The following list, adapted from Arthur A. Bright’s The Electric Lamp Industry (New York: Macmillan, 1949), contains over twenty predecessors or contemporaries . Notice that most used carbon; but Edison went one critical step further and used a thin filament of carbon, thus significantly increasing its resistance per unit length so that most of the electrical energy would be used in the lamps rather than lost in the distribution system. Date Inventor Nationality Element Atmosphere 1838 Jobard Belgian Carbon Vacuum 1840 Grove English Platinum Air 1841 De Moleyns English Carbon Vacuum 1845 Starr American Platinum Air Carbon Vacuum 1848 Staite English Platinum/iridium Air 1849 Petrie American Carbon Vacuum 1850 Shepard American Iridium Air 1852 Roberts English Carbon Vacuum 1856 de Changy French Platinum Air Carbon Vacuum 1858 Gardiner & Blossom American Platinum Vacuum 1859 Farmer American Platinum Air 1860 Swan English Carbon Vacuum 1865 Adams American Carbon Vacuum 1872 Lodyguine Russian Carbon Vacuum Carbon Nitrogen 1875 Kosloff Russian Carbon Nitrogen 1876 Bouliguine Russian Carbon Vacuum 1878 Fontaine French Carbon Vacuum 1878 Lane-Fox English Platinum/iridium Nitrogen Platinum/iridium Air Asbestos/carbon Nitrogen 1878 Sawyer American Carbon Nitrogen 1878 Maxim American Carbon Hydrocarbon 1878 Farmer American Carbon Nitrogen 1879 Farmer American Carbon Vacuum 1879 Swan English Carbon Vacuum 1879 Edison American Carbon Vacuum 92 edison’s electric light What was different about Edison’s lamp that enabled it to outstrip all the others? First, consider the requirements of a successful, individually controlled, moderately bright incandescent lamp. These requirements were not all obvious at the state of scientific and technical knowledge prevailing in the middle of the nineteenth century. With some advantage from hindsight, the three essential features of a lamp compatible with a practical lighting system are described below. Incandescent Material.A material was needed that could be heated electrically, without melting or otherwise disintegrating , until it glowed brightly enough to be useful, tolerable by the eyes at close quarters , and comparable to the then familiar gas jet or oil lamp (10–20 candlepower). Most serious investigators worked with carbon, which was readily available, inexpensive , and eminently successful in arc lamps, or metals like platinum, which had a high melting point and was chemically inert. However, inherent problems, many unpredictable at that time and stumbled into the hard way, stood in the path of success. High Vacuum.Appreciation of the need for a relatively high vacuum (of the order of 0.00001 atmosphere) developed slowly. Creating such a vacuum was inhibited by the lack of adequate pumps. Certainly, something had to be done to prevent a vulnerable incandescing element like carbon from oxidizing.The simpler expedient of enclosing it in an inert gas proved to cause an unacceptable (even if not recognized ) cooling effect.The gas conveyed heat from the lighting element to the enclosing wall, making it more difficult to maintain the element at an efficient incandescing temperature. (Some modern light bulbs contain substantial amounts of gas but have been specially designed to reduce heat losses.) Means for producing a sufficiently high vacuum did not become available until an improved form of the Sprengel mercury pump was introduced in the early 1870s. Even then, a hard-won vacuum could be lost if gas trapped in the incandescing material escaped when the lamp was first heated. Pumping had to be continued with the element heated in order to remove occluded gases before the enclosure was sealed. Before 1880 this final step was apparently taken only by Edison and Joseph Swan.Another problem that plagued Edison for a long time was sealing the glass envelope effectively, especially around the lead wires, to ensure retention of the high vacuum. Only Edison seems to have solved such problems satisfactorily.The evidence for Swan and others is not conclusive , but their failure to demonstrate consistently long lamp life suggests that they did not overcome their difficulties. Electrical Supply System and Lamp Resistance. Finally, there is the question of the electrical supply system and its characteristics in terms of desirable lamp resistance, system voltage, and conductor current. Before the 1870s it was natural to assume the use of batteries or magnetos (electromagnetic generators that were relatively inefficient because either the armature or the field used permanent magnets). These had technical limitations and high enough costs to make any centralized distribution system economically infeasible. At best, incandescent lighting would...