Pièce 118 - James David Forbes to William Whewell

4 pp

Edinburgh - References to Henri Victor Regnault's researches on steam and his formula are given in the Memoires de l'Academie des Sciences and occupy a whole volume printed in 1847. HVR's hygrometer [an instrument which measures the humidity of the air or other gases] is superior to Daniell's [John F. Daniell]: 'It acts by drawing air by aspiration through ether in a tube, whose exterior is silvered and receives the dew'. JDF has difficulty answering WW's question about the Polarity of Bismuth: 'My impression on reading Tyndall's paper was in his favour, but not quite confidently [John Tyndall. On the Existence of a Magnetic Medium in Space, 1855]. On the other hand I do not know what opinion Faraday has of late maintained. I confess that his language and that of Thomson (who is understood to agree with him) is almost metaphysically obscure and that Thomson in his later published correspondence with Tyndall seemed to me almost to admit the fact except in words'.