Georg Friedrich Brander (*1713;†1783), Augsburg.

Perspective sector, unsigned, ca. 1770.

Fig. 1: a perspective sector along with its cardboard slip-case, designed by 18th century Swiss mathematician, physicist and astronomer Johann Heinrich Lambert (*1728;†1777), as a mathematical aid to practitioners of perspective, i.e. draughtsmen, architects and artists. A similar perspective sector is featured as object of the month at the Kremsmünster Observatory Museum (see their website). Paper mounted on boxwood. 243x72x9mm.

Fig. 2: two views of each side of this unsigned sector, almost certainly made by prominent German instrument maker Georg Friedrich Brander, from an idea by Lambert. Bottom picture shows the side labeled Perspective Liniae which Lambert called the Perspectivische Seite (perspective side). In the top picture, designated as the geometrical side, another 5 pairs of lines, i.e. Lin. Arithm., Tang., Sectant., Sinus and Ellipt. The mounted paper is reproduced from the illustration of the Perspectiv-Proportionalzirkel in Lambert's treatise on the subject, published in 1778 [9].

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NOTES / REFERENCES

[1] BRACHNER, Alto; G.F. Brander 1713-1783 Wissenschaftliche Instrumente aus seiner Werkstatt, Deutches Museum, Munchen, 1983.

[2] Perspektiv-Proportionalzirkel von Georg Friedrich Brander: Objekt des Monats aus dem Museum der Sternwarte Kremsmünster, Juli 2004.

[3] STECK, Max; Johann Heinrich Lambert, Schriften zur Perspektive, Berlin, 1943.

[4] SCHNEIDER, Ivo; Der Proportionalzirkel: ein Universelles Analogrecheninstrument der Vergangenheit, München‎ 1970.

[5] SCHEFFELT, Michael; Instrumentum proportionum, oder Unterricht vom Proportional-Zirkel, Ulm 1697.

[6] BRANDER, Georg Friedrich; Beschreibung und Gebrauch eines geometrischen Instruments in Gestalt eines Proportionalzirkels, Augsburg 1780.

[7] GUNTER, Edmund; The Description and Use of the Sector, London, 1624. 
[8] GOLDMAN, Nikolaus; Tractatus de usu proportionatorii sive circini proportionalis, Leiden 1656. 

[9] LAMBERT, Johann Heinrich; Kurzgefaßte Regeln zu perspectivischen Zeichnungen vermittelst eines zu deren Ausübung so wie auch zu geometrischen Zeichnungen eingerichteten Proportionalzirkels, Augsburg 1772. 

[10] LAMBERT, Johann Heinrich; Jeden Perspektivischen Aufriß von freien Stücken und ohne Grundriß zu verfertigen, Zürich 1759.

[11] An illustrated French translation of the above. LAMBERT, Jean-Henri; La perspective affranchie de l'embarras du plan géometral, Zuric 1759.

[12] ANDERSEN, Kirsti; The Geometry of an Art, New York 2007.

[13] ERWIN TOMASH, MICHAEL R. WILLIAMS, The Sector: its history, scales, and uses.  

[14] Daniel Huber; Johann Heinrich Lambert: nach seinem Leben und Wirken, 1829 [Google Books]