Copy letter from Herbert Rix, to Mr F W Mason, 11 Great Sutton Street, Clerkenwell, E.C. 'Dear Sir, In answer to your letter of June 26th (which from press of work has unfortunately been laid aside longer than it should have been), I have to inform you that there is not, and never has been, any reward offered by the Royal Society for the solution of the problem of perpetual motion. I am, yours truly, H Rix Asst. Sec. R.S. [Assistant Secretary, Royal Society]'. 7 July 1891