Abstract :
THE conquest of dark by means of artificial illumination is considered one of the all-time greatest achievements of mankind. Nothing much can be accomplished in a dark environment. Over one hundred years ago, illuminating gas, carbon arcs, candles, kerosene, and other types of oil lamps were the most widely used artificial light in the world. In 1879, Edison invented the first practical electric lamp. This incandescent lamp marked the beginning of the electrical lighting industry.
