Invention Of Light Bulb

Geography has a great deal to do with who is credited with inventing the light bulb. West of the Atlantic, historians usually cite American inventor Thomas Edison; east of the Atlantic, credit usually goes to English chemist Joseph Swan.
There is considerable confusion and acrimony over whether it was Sir Joseph Swan (England) or Thomas Edison (USA) who invented the light bulb, but in fact their stories are inseparable - and in truth neither of them actually 'invented' the light bulb.

Sir Humphrey Davy (England) first demonstrated the principle of incandescent light in 1801 : that passing electricity through a filament will cause the filament to 'incandesce' of glow brightly. But the filament exposed to the air quickly burned away, so the inventors began to search for the way of isolating the filament from the air. During the 19th century some 18 inventors produced experimental incandescent bulbs before 1879, when Swan and Edison made their famous demonstrations.
As early as 1860, Swan patented the first experimental bulb to have a carbon filament. He announced the invention of a practical incandescent light bulb at a meeting of the Newcastle upon Tyne Chemical Society on 18 December 1878, but the filament had blow, and it wasn't until 18 January 1879 that he was able to make the world's first public demonstration, which he did during a lecture in Sunderland, England.
Meanwhile, in America, Edison was also investigating the light bulb, and sucessfully tested Model No.9 in his laboratory on 21 October 1879, 10 months after Swan's demonstration. Edison filed a patent for his bulb on 1 November 1879 (granted 27 January 1880) and made a public demonstration on New Year's Eve. Swan did not file his patent until 27 November 1880, more than a year after Edison's application in the USA.
Edison produced the world's first commercially available light bulbs in October 1880, a few months before Swan began production in England. When Edison applied for a British patent Swan began legal proceedings for patent infringement, but they settled out of courd and, in 1883 joined forces to form the Edison & Swan United Electric Company, whose bulbs were marketed under the name 'Ediswan'.

Source - The Book Of Inventions by Ian Harrison