Catalogue. A.H. Abbott & co., manufacturers and importers of mathematical and surveying instruments and drawing materials of every description .. (1896)
Abbott, A. H., & co., Chicago. [from old catalog] · [Chicago] · leaf 140
th micrometerfocusing arrangement, adjustable stadia hairs. Needle4^j inch, horizontal limb 6 inch, graduated to half de- •grees, two verniers at 45° reading to minutes, withhinged, white lined reflectors. Clamp and tangent screwsof German silver, tangent screws with counter spring.Shifting center.… … TRANSITS.
Drawing instruments
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