Giovanni Poleni bought this cylindrical mirror and some related anamorphosis paintings for the Cabinet of Physics of Padua University between 1739 and the end of December 1742. He catalogued them in his Indice delle Macchine as “A cylindrical convex mirror made of metal with six painted figures on six cardboards, monstrous: to show that their images are not seen as monstrous but beautiful. IIII.3.a.b.c.d.e.f.g.”

Date: 2nd quarter 18th century

Description

This cylindrical mirror, the only one still surviving from Poleni’s Cabinet of Physics, consists in a hollow cylinder of speculum metal inserted on a wooden support. A wooden sphere is screwed at the top of the mirror. There are also thirteen aquarelles on cardboard to be used with it. On each of these is written the alphanumeric code that Poleni assigned them according to their position in his Cabinet’s cupboards. Every painting looks deformed if one looks at it directly, while it appears corrected if one observes the mirror placed upon it. One  could thus show the students how light rays were reflected by cylindrical mirrors, enlightening how such mirrors were the so-called “mixed” mirrors, ie. “plane in a sense [vertical] & curved in the other [horizontal]” (Nollet). Anamorphosis were among the most well-known games in eighteenth-century cabinets of physics.

The images on the cardboards represent : 1- Man with a mask (marked “IIII.3.b”). 2) Man with a cloak (“IIII.3.c”). 3- Priest in a church (“IIII.3.d”). 4- Lobster (“IIII.3.e”). 5- Man who milks a cow (“IIII.3.f”). 6- Woman who looks at herself in a mirror (“IIII.3.g”). 7- Man with a hat (“IIII.3.h”). 8- A man sitting under a tree (“IIII.3.i”). 9- A sleeping giant (“IIII.3.j”). 10- A dog (“IIII.3.k”). 11- Bird on a branch (“IIII.3.l”). 12- Old begging woman (“IIII.3.m”). 13- Naked woman (“IIII.3.n”). Note that the existing cardboards are more numerous with respect to what Poleni noted in his Indice delle machine, as he probably bought at a later moment the ones marked with the letters from “h” onwards.

Materials and techniques: speculum/wood/cardboard

Dimensions: height 25 cm, diameter 6 cm

Related scholars: Giovanni Poleni (b.1683 - d.1761). Professor of Experimental Philosophy at the University of Padua from 1739 to 1761.

Keywords: optics, pre-cinema

University of Padua, Museum of the History of Physics

Cat. Number: 13

Bibliography

• Giovanni Poleni, Indice delle macchine, Biblioteca Nazionale Marciana di Venezia, mss.it., cl. III, 54-55 = 4969-4970, cl. IV, 626 = 5488, 636 = 5497 [It was written by Giovanni Poleni from 1740 to 1761]
• Jean Antoine Nollet, Leçons de physique expérimentale, 6 vols., Paris, 1a ed., 1743-1764