Gabriel Lippmann

“Every hypothesis must be verified, or it must be abandoned.”

“I have thought of a method of fixing the image of the spectrum, with the colors. It is the photographic image of the mirror itself.”

“It is the luminous vibration itself which is fixed on the sensitive layer, so as to form there a persistent mold.”

“The basis of the method is simple. The sensitive film is placed in contact with a reflecting surface, a mirror of mercury.”

“The incident light, after passing through the glass plate and the sensitive layer, is reflected by the mercury and interferes with the direct incident light.”