Searchlights have recently been made capable of being seen nearly a hundred miles away. Such lights are very valuable for signaling purposes in time of war, and they are also much used on warships, enabling the officers to detect the approach of an enemy in the dark and to guard against torpedo boats.

Photo by Brown Bros. LONG RlBBONS OF LlGHT.

The giant scintillator erected on the shore of the bay was not the least wonderful of all the wonderful sights of the Panama-Pacific Exposition at San Francisco.

We are all familiar with the less powerful ones which are universally used on automobiles for night driving and in a multitude of other every-day practices. The illustration shows a battery of powerful searchlights, the use of which furnished some very effective displays during the Panama-Pacific Exposition at San Francisco in 1915.

Searchlights are ordinarily electric arc lights of great candle-power, arranged with a parabolic reflector so that the rays are sent almost wholly in one direct line, forming a path of light which may be projected for miles.