Copy letter, from Sir John Herschel to Michael Faraday, dated at [Devonshire Place] Contemporary copy in sender's hand, signed by sender. Informs Michael Faraday that John Frederick William Herschel has been called to serve on a grand jury and so may have to miss some glass subcommittee meetings. [This note enclosed the letter written by John Frederick William Herschel on 1827-11-6.] 9 November 1827