25 MILLION-CANDLEPOWER SEARCH LIGHT
Using three small capillary water-cooled mercury lamps, instead of the customary carbon arc, General Electric has developed a new 25-million-candlepower searchlight. R.E. Clisdell, G-E lighting specialist, is shown with a complete unit and holding one of the small mercury light units in his hand.
As there are no carbons to be replaced or adjusted, the new searchlight will function by itself. First use of the new searchlight will be made in re-lighting the tower of the General Electric Building in New York City.
In the new type searchlight, three of the high-pressure mercury lamps, each rated at 1,000 watts and no larger than a cigarette in size, are mounted close together. Despite the enormous candlepower produced, little heat is generated. Seventy per cent of this is removed by pumping 90 gallons of water an hour through the cooling jackets of the lamps.
The cooling system, mounted in a small box beneath the searchlight,
removes heat from the water much after the fashion of an automobile
radiator, and feeds it back through the lamp jackets. Control equipment
is also contained in the box and the lights can be started automatically
on a prearranged schedule with aid of an x astronomic time switch.
Though more convenient, the new searchlight is still below the present
high intensity searchlight in beam candlepower and effectiveness.