1 books for « lehmann johann georg ... »Edit

‎Darstellung einer neuen Theorie der Bezeichnung der schiefen Flächen im Grundriß oder der Situationszeichnung der Berge.‎

‎Leipzig, Johann Benjamin Georg Fleischer, 1799. Contemp. hcalf. Gilt spine. Titlelabel with gilt lettering. A paperlabel pasted on top of spine. Stamps on title-page. XX,172 pp. and 4 large folded plates. A few brownspots to the first few leaves.‎

‎Scarce first edition. Here Lehmann standardized the Hachure Representation. Hachures are an older mode of representing relief. They show orientation of slope, and by their thickness and overall density they provide a general sense of steepness. Being non-numeric, they are less useful to a scientific survey than contours, but can successfully communicate quite specific shapes of terrain. They are a form of shading, although different from the one used in shaded maps. - Poggendorffr I, 1410.‎