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 126
in these instruments will give the value of angles, as follows: The anglewhich has been ascertained from the divided arc on the instrument refers to that degree in thecolumn which is marked angle. In the opposite column will be found the fall or rise in anygiven distance. For instance, say the…
Drawing instruments
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