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“That one, then. The roll unwinds. The selenium cells transform the light impulses into sound waves, and . . .” “And there you are,” Dr. Gaffney concluded.

Stebbins of Urbana has been very successful in its application and he discovered the secondary minimum of Algol with the selenium cell.

Moreover, the light passes right through the photograph and falls upon a mirror inside, off which it is reflected on to a selenium cell.

Form of selenium cell used by Bell and Tainter 110 54.

The assistant had shoved the photograph into the holder from which each section was projected on the selenium cell screen.