Austro-Daimler is an Austrian brand; it's likely English thread but we can't rule out French or even Swiss for that matter. Are there any markings on the cups? If you're lucky, the threading will be explicitly labeled there, e.g. "1.37 x 24" or "35 x 1." Otherwise, more arcane markings may indicate threading, e.g. inscribed rings or lack thereof, hexagon or octagon fixed cup shape, knurling patterns on the lockring, etc.