From the earliest periods of history until the beginning of the 19th
century, fire was man’s primary source of light. This light was
produced through different means—torches,


, oil and gas lamps. Besides the danger presented by an open flame
(especially when used indoors), these sources of light also provided
insufficient illumination.

The first attempts at using electric light were made by English chemist
Sir Humphry Davy. In 1802, Davy showed that electric currents could heat
thin strips of metal to white heat, thus producing light. This was the
beginning of incandescent (defined as glowing with intense heat) electric
light. The next major development was the arc light. This was basically
two electrodes, usually made of carbon, separated from each other by a
short air space. Electric current applied to one of the electrodes flowed
to and through the other electrode resulting in an arc of light across

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