Keywords: Borda repeating circle, Etienne Lenoir, Paris, c. 1790 - Mathematisch-Physikalischer Salon, Dresden - DSC08127.JPG en Exhibit in the Mathematisch-Physikalischer Salon Zwinger Dresden Germany This artwork is old enough so that it is in the public domain Photography was permitted in the museum without restriction 2013-12-08 07 51 12 own Daderot other versions PD-old-70 cc-zero Optical instruments in Mathematisch-Physikalischer Salon Zwinger Dresden Uploaded with UploadWizard Reflecting circles Étienne Lenoir instrument maker Jean-Charles de Borda |