Copy letter from Herbert Rix, to H M Paul, Librarian, United States Naval Observatory, Washington In answer to Paul's letter of 31 March, Rix assumes that the question of an equivalent of exchange did not enter into the calculation of the Committee in assigning Series A to the Observatory's library. Paul's request for both series of the 'Philosophical Transactions [of the Royal Society]' shall be laid before the Committee when they next meet. Rix explains that Series B is exclusively biological. The Krakatoa volume was not placed upon the Royal Society's list of works for gratis or exchange but he will nevertheless submit Paul's request for a copy. 10 April 1890