Letter, from Fedor Thomas to Sir John Herschel, dated at 5 Quai d'Anjou, Paris Autograph letter signed by sender. Not too familiar with John Frederick William Herschel's work, as FT's work has taken him out of the area of John Frederick William Herschel's interest. Has very limited time for mathematics, but indicates his current interest. Refers to some writings of FT on topics of weights, measures, and monetary matters. 14 May 1864