Secretan, Marc Francois Louis
Brief Bio: 1804-1867, mathematician; scientific instrument maker, Swiss
until 1844 - professor of mathematics at Academy of Lausanne;
1840 - worked with Friedrich von Martens and Samuel Heer producing daguerreotypes;
1844 - moved to Paris;
1845 - partnership with Lerebours as Lerebours & Secretan; used joint name until 1880s and beyond.
1855 - after retirement of Noel Paymal Lerebours became sole proprietor of Lerebours and Secretan, and signed