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 59
47 ANGLES. through the point found by the intersection of the arcs, and a b c is an angle of 60°. To draw an angle of 30° geometrically: — With centre b (Fig. 41), describe the arc 1, 2. A Fig. 41. With the centre 1, and the same radius, describe the arc B 3. With centre 2, and the same radius,… … Fig. 42. given angle, as a b c (Fig. 42) : — With b as centre and any radius, describe the arc 1 ; with 1 as
Sheet-metal work
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![An illustration from Nicolai Copernici Torinensis De reuolutionibus orbium coelestium, libri VI : Habes in hoc opere iam recens nato, & aedito, studiose lector, motus stellarum, tam fixarum, quàm erraticarum, cum ex ueteribus, tum etiam ex recentibus obseruationibus restitutos: & nouis insuper ac admirabilibus hypothesibus ornatos. Habes etiam tabulas expeditissimas, ex quibus eosdem ad quoduis tempus quàm facillime caculare poteris. Igitur eme, lege, fruere. [Line in Greek] (1543)](https://img.insideoutlibrary.com/img/200/ia-nicolaicopernici00cope-357-249.webp)
