Letter, from George A. MacFarren to Sir John Herschel, dated at 7 Hamilton Terrace Autograph letter signed by sender. Appreciates John Frederick William Herschel's beautiful simplification of the numerals in musical arithmetic. Wishes John Frederick William Herschel would give up the point of the variability of the supertonic and transfer it to the submediant. Agrees with John Frederick William Herschel over the need for a keyboard instrument possessing a perfect chromatic scale in any particular key. 21 November 1868