The solution was a vacuum cap that sits over the whole unit, much like the glass globe surrounding the tungsten filament in a flashlight bulb.

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Edison bulbs function by making a Tungsten filament very hot, and a hot object glows: radiating energy on a broad spectrum of wavelengths, only a small part of which is visible to the eye.

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As with many other products--including tungsten-filament lightbulbs, X-ray machines and jet engines--GE bought patents from an inventor to get into the turbine business, then refined the design and manufacturing techniques ( see time line).

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