Letter, from William Rutter Dawes to Sir John Herschel, dated at Hopefield, Haddenham, Thame Autograph letter signed by sender. Is grateful for his prompt reply about his father's papers on double-stars. Had no idea that Angelo Secchi's Means were so inaccurate. Gives the principle on which his own Means are based. The weather has been wretched and most unsuitable for any observations. 8 January 1868