In response to JH's comments on JT's explanation of comets says faintness of head and nucleus does not indicate non-existence; eye may not see all. Experiments with polarized light produce 'gorgeous' 'residual blue.'

Encloses reference to one of JH's letters to JT that has already been printed.

Is delighted with JH's exposition of colors of thin plates and of measurements of a wave of light in Familiar Lectures. Asks permission to quote from it.

Thanks for work on diamagnetism and magne-crystallic action [Researches on Diamagnetism (1870)], which JH is excited to read. Mentions long-abandoned plans for magnetization experiments. Envies those who can see JT's 'magic' experiments at Royal Institution.

Gratified by JH's 'sympathy and approbation,' and that JH's writing and spirit remain 'firm' and 'fresh.'

Thanks for paper on action of rays 'of high refrangibility' on gases and vapors. Attempts to understand reflection of wave motion on particles with diameters 'incomparably smaller' than length of wave.

Thanks for suggestion-filled letter. Remarks on blue color of water.