How Does It Work?

    Thomas Edison had first invented the lightbulb in 1879,  but kept improving upon it until 1880. Edison and his assistants would work hour after hour creating around 3,000 different designs for the incandescent light bulb. Finally, they came up with the idea of a filament inside a glass vacuum bulb. Edison would have the glass bulb created in his own glass blowing shed. The tricky part was getting it to light up. The idea was that the filament inside the bulb would be made so hot that it would glow. The problem was finding a material that would sustain the glow for a long period of time without burning out. Edison carbonized more than 6,000 materials trying to find a suitable filament. 
    He even had scientists abroad send him tropical vegetation fibers. Finally, Edison tried to carbonize a cotton filament. Once given power, the bulb glowed for fifteen hours, then died out. Bouncing off of the cotton, Edison found that carbonized bamboo could burn for over 1200 hours. 


            http://www.ourdocuments.gov/doc_large_image.php?flash=true&doc=46
         http://www.history.com/topics/thomas-edison/videos#light-bulb-turns-night-into-day

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(Refer to above diagram) A= glass bulb, B= filament, C= support, X= the metal, Metal tip connects the bulb to the lamp.