The sheet-metal worker's guide : a practical handbook for tinsmiths, coppersmiths, zincworkers, etc., comprising numerous geometrical diagrams and working patterns, with descriptive text (1888)
Crane, W. J. E. (W. J. Eden) · London : Lockwood and Son · leaf 47
e termed concentric (c. Fig. 26). Parallels or parallel lines are those which are everywhere the same distance apart, and which if produced or lengthened for ever, would never meet (see a and b. Fig. 26). A horizontal line is one perfectly level, a vertical line is one perfectly upright, having… … Fig. 27. the strict sense, but may incline to or even be parallel with the horizon line. (The horizon is the line where sea and sky appear to meet when one looks from the shore.) It is thus clear that while a vertical line is perpendicular to a horizon- tal one, a horizontal line is perpendicular…
Sheet-metal work
Internet Archive · Getty Research Institute · Public domain (published before 1931). Free to use for anything.
