Copy letter from Robert William Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society The publication in the 'Proceedings [of the Royal Society]' of a supplementary note by Mr Tutton on the subject of his recently archived paper was conditional on Callendar reporting on the question of the agreement of his results with those of Fizeau. The exact point to be decided is contained in the enclosed letter from Professor George Carey Foster [not enclosed]. Asks if Callendar requires the full paper to report. 20 July 1899