Letter, from Humphrey Lloyd to Sir John Herschel, dated at Kilcroney, Bray Autograph letter signed by sender. Has not seen the paper in the Smithsonian Institution, but believes the author is in error. Has looked at A. L. Cauchy's Dispersion Memoir, but thinks Baden Powell's paper presents a more distinct formula. Hopes to send in a few weeks the first volume of Humphrey Lloyd's [Observations Made at the Magnetic and Meteorological Observatory at Trinity College, Dublin]. 5 June 1865