This photocell has the light sensitive cathode deposited on the inside of the envelope. The anode is a small bucket in front and below the cathode.
The presumption is that this photocell is sensitive into the UV region. The clue being in the Type designation.
The paper label carries the serial number of 765 and the maximum anode voltage of 100 Volts.
The anode is probably the small cup seen on the right but there is also a metal rectangle that defines the viewing angle. This also could be a collector of photo electrons - we have no operating details.
Face view of the cathode, anode and box.
The box structure is not in contact with the cathode surface. The cathode only connects to the top cap.
The side window envelope is 30 mm in diameter and, excluding the B4 base pins, is 107 mm tall.
