EuropeanWeston Electrical Instrumentation Co.Newark NJ. BerlinNO. 8843
The presence of mica suggests (to me) high temperatures.
My conclusion is that it is a 1nF capacitor for 300V,
it might be a calibrated resistor
My DVM reports opencircuit.
The problem with that is the people didn't use the units of nF in those days its use is relatively new, it would have been called a 1000pF capacitor.