Copy letter from Herbert Rix, to Dr John Scott Burdon Sanderson, Fellow of the Royal Society 'Dear Dr Sanderson, There is no way of adding to an old certificate: but, by a statute quite recently passed, you can, if you please, take out a supplementary certificate which, however, has to be signed by six Fellows, in addition to the signatures already attached to the original certificate. I note what you say about Prof. Ewert's paper and the two certificates of Professors Ewart and Gotch have been re-suspended. I am, yours truly, Herbert Rix Asst Sec RS [Assistant Secretary, Royal Society]'. 4 February 1892