Worthen, William Ezra, 1819-1897, [from old catalog] ed · New York, Appleton · leaf 24
ersections draw theline 0 D. It will be perpendicular to the line A B, and bisect or divide it intotwo equal parts. If the line A B be considered the chord of a circle, its centre would lie inthe line C D. This construction is sometimes used merely to divide a line into two equalparts, or bisect… … Fig. 15. Central point; if the other point then falls exactly on the opposite extremityof the line, it is properly divided; but, if the point falls either within or with-out the extremity of the line, divide the deficit or excess by the eye, inhalves, and contract or extend the dividers by this…
Mechanical drawing
Internet Archive · Library of Congress · Public Domain Mark 1.0. Free to use for anything.
![An illustration from L'optique divisée en trois livres : ou, l'On démontre d'une maniere aisée tout ce qui regarde 1. la propagation & les proprietez de la lumiere. 2. La vision. 3. La figure & la disposition des verres qui servent à la perfefectionner [sic] (1682)](https://img.insideoutlibrary.com/img/200/ia-loptiquedivise00ango-81-10.webp)