The V1923/D is a Trigatron or triggered spark gap. The device is cold cathode and the envelope is probably gas filled. In use short duration high energy pulses are delivered to the load - most probably a magnetron.
This type of device was used to simultaneously fire the 32 charges that initiated the implosion of a nuclear weapon where the detonator contained wire that was vaporised at firing.
Normally these have protective basket glued to the envelope to contain the glass in the event that it splinters in use. The CV100 is the usual form of the trigatron.
The anode connects to the top pin and built above the pinch are the main electrode and within the smaller trigger.
This close-up shows the central trigger electrode.
The open base has two stranded wires connected to the triangular contacts.
The wide glass tube envelope is 65 mm in diameter, and excluding the base pins is 150 mm tall.
Updated November 20, 2017.