Unpublished letter, 'Addition to a memoir on the determination of unknown functions that are evolved under definite integrals' from J [Joaquim] Gomes de Souza to [William] Sharpey In a previous communication (see AP/38/26), de Souza developed φx in terms of the function A emrx. In the present communication he develops in a more general way, using terms of the form Ar ∫δrexwϖ (ω1mr)dω, the function of ϖ being assumed at pleasure. Includes one figure in the text. Subject: Mathematics / Calculus Received 17 November 1856. Read 12 February 1857. Communicated by Sharpey. Written by de Souza at 4 Rue des Beaux-Arts, Paris. Whilst the Royal Society declined to publish this paper in full, an abstract of the paper was published in volume 8 of the Proceedings of the Royal Society as 'Addition to a memoir on the determination of unknown functions that are evolved under definite integrals'. 27 October 1856