This plate was found 60 years ago in Petiot-Groffier photographic Laboratory, where 30 years later a long manuscript letter sent by Richebourg to Petiot-Groffier was enearthed, giving many important details, finally published in 2009:
"According to my promise, I enclose my portrait made at 1 o'clock in the afternoon on Thursday, July 1, 1841. In 7 minutes in the shade by a weather too clear to allow me to open the eyes… This gives it an unflattering aspect because I look very unkind. I have placed several catalogs so that you can get acquainted with all that is necessary in the exploitation of science. Don't forget to mark if you have to write everything in English."
