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Two identical units each provided with Polaroid disc mounted in a rotatable mount, wtih aperture of 25mm, and a pointer traverses a 75 mm dia brass scale divided into 360° x 1. ...
Two identical units each provided with Polaroid disc mounted in a rotatable mount, wtih aperture of 25mm, and a pointer traverses a 75 mm dia brass scale divided into 360° x 1. ...