At a joint meeting of the French Academy of Sciences and the Académie des Beaux-Arts held at the "Institut de Françe" on Monday, 19 August 1839François Arago briefly referred to the earlier process that Niépce had developed and Daguerre had helped to improve without mentioning them by name (the heliograph and the physautotype) in rather disparaging terms stressing their inconvenience and disadvantages such as that exposures were so long as eight hours that required a full day's exposure during which time the sun had moved across the sky removing all trace of halftones or modelling in round objects, and the photographic layer was apt to peel off in patches, while praising the daguerreotype in glowing terms. Overlooking Nicéphore Niépce's contribution in this way led Niépce's son, Isidore to resent his father being ignored as having been the first to capture the image produced in a camera by chemical means, and Isidore wrote a pamphlet in defence of his father's reputation "Histoire de la decouverte improprement nommé daguerréotype(History of the discovery improperly named the daguerreotype)