Sight by Jacob Keser
From Inventions
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Inventor
Jacob Keser
Historic Period
ca. 1530
Description
Illustrated by Albrecht Dürer in the second edition of his treatise on geometry (1538), the instrument was invented by a certain Jacob Keser, described by Dürer as a particularly ingenious individual. This device eliminated the operational limitations of the glass, where the viewing point had to be close enough to let the painter draw directly on the glass. With Keser’s device the painter, looking through a sight "as you would do with a rifle", could draw directly on the glass although positioning the “eye”, that is, a hook in the wall, at any distance. The sight was tied to the hook and had an adjustable finder so that the observer’s eye always remained on the line joining the hook to the finder, regardless of the distance. A well-known engraving by Jost Amman suggests that Keser’s invention had a certain success in the cartographic field, in representing birds-eye views of cities. For a variant of this instrument, see Ludovico Cigoli’s sight.
Bibliographical Resources
Dürer, Albrecht, Underweysung der Messung, mit dem Zirckel und Richtscheyt : in Linien Ebnen vo gantzen Corporen / durch Albrecht Dürer ..., Gedruckt zu Nürenberg : Durch Hieronymum Formschneyder, 1538, IV.
Author of the entry: Filippo Camerota
