26 MICROSCOPES, TELESCOPES, PHOTOGRAPHIC OBJECTIVES, MAGNIFIERS, GEODETIC AND NAUTICAL TELESCOPES; SPECTROSCOPES, SPECTROMETERS AND SPECTROGRAOGSL RETRACTOMETERS; INTERFEROMETERS; PHOTOGRAPHIC CAMERAS; PROJECTORS; PHOTOGRAMMETRIC CAMERAS AND PLOTTING INSTRUMENTS; AERIAL SURVEY CAMERAS AND ACCESSORIES; RECTIFIERS FOR THE RECTIFICATION OF AERISL PHOTOGRAPHS; STEREOSCOPES FOR VIEWING AND MEASURING STEREO PICTURES; SLOT CUTTING EQUIPMENT FOR RADIAL TRIANGULATION; AEROSKETCH MASTERS;FILM DEVELOPING OUTFITS; OPERATION MICROSCOPES, SLIT-LAMP MICROSCOPES; SPECTACLELENSES, SPECTACLE FRAMES; PHOTOELECTRIC PHOTOMETERS, COLORIMETERS, REFRACTOMETERS, POLARIMETERS AND ELECTRICAL GAUGES.