Letter, from William Henry Smyth to Sir John Herschel, dated at 3 Cheyne Walk, Chelsea Autograph letter signed by sender. Requests copy of John Frederick William Herschel's observations made in 1811. Asks latest opinion of John Frederick William Herschel on Gamma Virginis before the publication of his Cycle of Celestial Objects for the Use of Naval, Military, and Private Astronomers. 6 June 1843