Letter, from Thomas Young to Sir John Herschel, dated at 48 Welbeck St. Autograph letter signed by sender. J. J. Littrow's paper in F. X. von Zach's April [Correspondence astronomique, geologique, hydrographique et statistique] is only 'a new hash' of [F. W.] Bessel and no improvement. 1826-6 or earlier