Thomas Edison of the Edison patent to charge a more reasonable rate for the use of the Edison patent rights and lowering the price of the electric lamp. On October 8, 1883, the US patent office ruled that Edison's patent was based on the work of William E. Sawyer and was, therefore, invalid. Litigation continued for nearly six years, until October 6, 1889, when a judge ruled that Edison's electric light improvement claim for "a filament of carbon of high resistance" was valid. To avoid a possible court battle with Joseph Swan, whose British patent had been awarded a year before Edison's,
Carcel lamp Carcel lamp The Carcel lamp was an efficient lighting device used in the nineteenth century for domestic purposes and in France as the standard measure for illumination. The lamp was invented by the French watchmaker Bernard Guillaume Carcel (1750–1818) to overcome the disadvantages of the Argand-type lamps then in use. The vegetable - mostly colza - oils then available were thick and would not travel far up a wick. The Argand lamps used a gravity feed which meant that the oil reservoir was located above the burner, casting a shadow and making the lamp top heavy. Carcel designed a lamp