A London encyclopaedia, or universal dictionary of science, art, literature and practical mechanics : comprising a popular view of the present state of knowledge : illustrated by numerous engravings, a general atlas, and appropriate diagrams (1829)
Curtis, Thomas, fl. 1820 · London : Thomas Tegg · leaf 800
hich is parallel to the long ruler, the copy willbe greater than half the original. The construction of this instrument requires adegree of accuracy which most of our instrument-makers are strangers to; for which reason thereare very few of the instruments that succeed.Few will do any thing… … P the pencil for tracing the given figure P P,and p the pencil which traces the other figuiepp;p, &c., must be so adjusted, that p, C, and P,may lie in one straight line ; then, since B/j : Ap y. B P : A C, whatever be the situation of thepentagraph, the angles P C P and pCp, are ver-tical :…
Encyclopedias and dictionaries · Aeronautics
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