It was there, too, that he began that wonderful series of experiments which gave to the world the incandescent lamp.

He had noticed the growing importance of open arc lighting, but was convinced that his mission was to produce an electric lamp for use within doors.

Forsaking for the moment his newborn phonograph, Edison applied himself in earnest to the problem of the lamp.

His first search was for a durable filament which would burn in a vacuum.

A series of experiments with platinum wire and with various refractory metals led to no satisfactory results.