Copy letter, from Sir John Herschel to Joseph Nicolas Nicollet, dated at 9 Downing St. Copy of a letter. P. L. Guinand has informed the Astronomical Society that he can make flint glass free from the usual imperfections. Would like any information from JN. One of his papers has been named as likely to receive a prize. Hears that an arithmetical machine has recently been demonstrated before the Institute. Have any details been made public? 20 April 1822