|François Arago who announced the first complete practical photographic process at a meeting of the French Academy of Sciences, on 7 January 1839 and followed all the first public developments.
Earlier in the century, the main dispute in the Academy and all the scientific community was about the classical particle and wave theories of light.
François Arago had been a fierce supporter in the 1810s of the wave view, against the ray and particle view, but this opinion began to dominate scientific thinking about light only in the mid 19th century. Among his friends, Alexander von Humboldt was on the same side, when Jean-Baptiste Biot was then on the opposite side following Laplace.
It is interesting to note than when Daguerre visited Arago on late 1838, the Perpétuel sat down with both Humboldt and Biot to evaluate the invention. The same scholars who had argued on the theory of light 30 years before were now gathering to study together its effects and persistent shadows on a polished silver mirror.
The other Perpétuel was Pierre Flourens, a physiologist who prove that the mind was located in the brain, not the heart, through the study of ablations on numerous animals, also a pioneer in anesthesia. Pierre and François worked together for twenty years as François was permanent secretary, maths section, betwen 1830 and 1853, when Pierre was between 1833 and 1868. And when Arago passed away, Flourens took over the various presentation of improvement in the field of scientific photography …