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The plume so intensely darkened the sky that street and residential lights with photocells designed to turn on at dusk were illuminated — human technology tricked by the inferno.

You can set the lights to come on and go off at any time you choose or use the photocell and have them on at dusk and off at dawn.

The miles of relays and photocells had given way to the spongy globe of plantinumiridium about the size of a human brain.

The young Arthur received cast-off equipment, such as telephones, switch-gear and a photocell from his relative George Grimstone, an engineer who taught him to build wireless crystal sets.

Today we combine a laser and a photocell, or a radar transmitter and a radio telescope, and in this way make active contact by light with distant objects.