itudes and longitudes accurately read off maps and charts. It will serve as a diagonal scale or vernier for exact measurements of various kinds, and can be put to numerous other uses. As will be seen from the illustrations, it is extremely neat and compact, and the special arrangement does not… … Fig. 4. Open the divided arm D E to any convenient position and clamp it. Move the arm A B until its inner edge accurately cuts the looth division on the scale of D E. Then with the arms thus set, place the instrument so that the whole line is exactly enclosed between the inner edges of the two…
Internet Archive · Smithsonian Libraries · Public domain (published before 1931). Free to use for anything.
