The 1807 is a directly heated full wave rectifier dating from the early 1930s. The construction follows what became the standard pattern of anode shape and ribbon filament. Our other 1807 looks to be of an earlier construction.
The glass rod insulators that hold the filament tension springs and the inverted V of the oxide coated filament ribbon.
The pinch and lower supports.
The identification is confined to the dome.
The balloon envelope is 54 mm in diameter, and excluding the B4 base pins is 119 mm tall.
Reference: Datasheet. Type 1807 was first introduced in 1932.