WWII German Luftwaffe OCULUS G.M.B.H. SPEZIALFABR. OPT. APPARATE BERLIN-N4 NO.676 Compass
二戰，德國空軍，OCULUS高精度測量用羅盤，序號：676號《Black Water Museum Collections | 黑水博物館館藏》
According to collector George Fulford's notes:
You can see at a glance this is a fine piece of optics. It has German written all over it. It's housed in a green leather 7 by 5 inch box inside which is stamped a German Eagle and a XXXX
This dazzling little jewel was used for surveying front-line airfields. The fact that it can measure to minutes of the arc is impressive and totally unnecessary, but it is an indication of the German trait for quality and accuracy. I remember my younger days flying in post war France and my Flight Commander casually pointing out to us a field that he had flown Spitfires from in 1944, and I know the field did not get an ounce of survey beyond looking for it being long enough to fly Spitfires from.