The First Book of the CrossStaffCHAPT. IV The use of Lines of equal parts joyned with the Lines of Chords.The Lines of equal parts do serve also for protraction, as may appear by the former Diagrams, but being joyned with the Lines of Chords, which I place upon one side of the Cross, they will further serve for the protraction and resolution of right Lined Triangles; whereof I will give one example in finding a distance at two stations otherwise than in the Second Chapter. Let the distance required be AB, at A the first station, I make choice of a station Line towards C, and observe the Angle BAC by the Tangent Lines, which may be 43 gr. 20 m. then having gone an hundred paces toward C, I make my second station at D, where suppose I find the Angle BDC to be 58 gr. or the Angle BDA to be 112 gr. this being done, I may find the distance AB in this manner.


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