Ploessl, Georg Simon

Ploessl, Georg Simon (1794-1868)
Simon Ploessl was born in 1794 in Wieden, in the vicinity of Vienna. He learned the art of woodworking by his father, a cabinet maker and in 1812 he began working at Voigtländer, one of the oldest optical product firms (established in Vienna in 1756 by Johann Christoph Voigtländer). He studied mathematics and optics and founded his own optic laboratory in 1823 at his father's house, at Freundgasse in Vienna. In 1845 36 skilled workmen were under his employment at his laboratory at 215 Feldgasse Street.

Richard, Jules

Société anonyme des établissements Jules Richard
25, rue Mélingue, Paris

The firm Richard, founded in 1858 made mainly barometric instruments

Rohrbeck, W.J.

W.J. Rohrbeck's Nachfolger, Wien I., Karntnerstr. 59

Chemistry and physics equipment.


Ruhmkorff, Heinrich Daniel

Heinrich Daniel Ruhmkorff (Rühmkorff) (January 15, 1803 in Hanover – December 19, 1877 in Paris) was a German instrument maker who commercialised the induction coil (often referred to as the Ruhmkorff coil.)


Marc François Louis Secrétan (1804 - 1867), born in Lausanne, professor of mathematics at the Academy of Lausanne, moved to Paris in 1844. In 1845, he joined Lerebours and the firm "Lerebours et Sécrétan" used that name until 1880's and beyond. Sécrétan became head of Lerebours et Sécrétan after 1855.