Electrical medical lamp. Historical artwork of an early electrical lamp being used to examine a patient's mouth and throat. The wire (far left) provides power for the lamp, which uses an incandescent sealed bulb with a helical platinum filament. A headband holds the lamp in place on the doctor's forehead. The doctor is using a tongue depressor, as well as a cloth to absorb the patient's saliva. The principle of the electric light bulb was demonstrated by Humphrey Davy in 1801. The first endoscopic device that used an electric lamp was built in 1869 by the French inventor Gustave Trouve (1838-1902). Artwork from A Travers l'Electricite (G. Dary, Paris, 1900).