Letter, from Sir John Herschel to Richard Sheepshanks, dated at Collingwood Autograph letter signed by sender. Invites Richard Sheepshanks to dinner in Collingwood on 10 [July], as F. G. W. Struve will be there. U. J. J. Leverrier may also come, but G. B. Airy and John Lubbock cannot attend. 1? July 1847