This valve was donated to the museum with a heavy base that had been used to make a display of the device. It lacks any identification.
Clearly this is a power triode with a graphite anode. It would have a high anode voltage as the insulators are ceramic and substantial.
The eight pins emerging from the hard glass base. Only four have wires attached and it is probable that the original base was four pin only.
The image shows the four filament supports and tension springs. The filament itself passes through the grid eight times and on test at 10 Volts takes around 5 Amps.
The wide glass tube envelope is 82 mm in diameter and, excluding the 8 base pins, is 227 mm tall.
Updated July 03, 2020.