hands while working.

In 1906, the tungsten filament was introduced and used to produce 200 to 3,000 candlepower incandescent dive lights. The Siebe Gorman & Company introduced a 250-watt mercury vapor hand lamp in 1919 that could produce as much as 18,000 candles. For diving in turbid water, 45-watt Sodium hand lamps became the preferred choice. These early lights had to be turned on underwater to avoid cracking the heated glass as it entered cold water.

The

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