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Jehl stands on stepladder pouring mercury into vacuum pump, while Edison turns a valve.

Edison and Francis Jehl reenacting the evacuation of an experimental light bulb during dedication ceremonies at Dearborn.

In the picture, Jehl is pouring mercury into a network of glass tubes; this was an effective evacuation pump (designed by Edison on the basis of pumps by Heinrich Geissler and Hermann Sprengel) that sucked air out of the light bulb.

SI negative #87-1732

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The Challenge of Success
Before Forty
Changes At Forty
Home Life
The New Technical World
Fame And Its Distractions
Edison In His Eighties