The 1904 is a current stabiliser for use on series heater chains running at 100 mA. The current is stabilised for voltages across the tube of 30 - 80 Volts.
The lettering is the Type designation, Philips and Made in Holland.
The thin iron wire is looped around the envelope.
The wide glass tube envelope is 36 mm in diameter, and excluding the B4 base pins is 90 mm tall.
Reference: Data-sheet. Type 1904 was first introduced in 1928. See also1928 adverts.
