The ORP60 is a cadmium sulphide light dependent resistor. The active surface faces the clear dome of the envelope.
The maximum dissipation is 70 mW @ 25 °C. When in the dark the maximum voltage across the device is 350 V. In the light the resistance falls to 60 kOhms.
The dark rectangle near the top is the active element. It looks like a modern surface mound resistor.
The light would be focussed on the dome.
The thin glass tube envelope is 5 mm in diameter, and excluding the base pins is 15 mm tall.
Reference: Data-sheet. Type ORP60 was first introduced in 1959. See also1959 adverts.
