Thanks for and comments on paper and lectures on 'diathermancy &c' of gases, scientific teaching, and solar chemistry. Regrets that JT mentioned all names connected with light research except JH's. Remarks on absorption of light, molecular vibrations.

Apologizes for not having seen JH's paper on spectra of colored flames and thus having overlooked JH's prior claims [see JH's 1861-7-21]. Will try to make amends.

Reply to JT's 'Remarks on Radiation and Absorption.' Calls non-absorption of air and vapor key to understanding meteorological phenomena. Remarks on 'radiant heat' from moon.

Gives account of observations on lunar radiation, including detailed description of experiments.

Does not believe surface of moon can radiate cold; perhaps new moon can. Explains this geometrically.

Clarifies that JT does not believe moon radiates cold itself, but effects are 'as if' it did. Relates this to atmosphere.

Finds JT's work on thermotics 'highly interesting,' although criticizes measurements of 'tenuity' of vapor, and explanation of scattering of sunlight and formation of corona around moon during eclipse.

Remarks on JT's papers on radiant heat and related role of moisture. Will send requested sample of rock salt. Explains difficulties using it and hopes JT will have better success, perhaps even repeating JH's experiments.

Finds JH's approval incredibly gratifying. Thanks for gift of rock salt. Is sending unscientific book; trusts JH's interests are broad enough to appreciate it.

Asks permission to print extract of JH's letter on heat spots of spectrum of rock salt sample. Hopes JH's son [Alexander] will speak at Royal Institution; JT would help with illustration. Wonders how blue color of water relates to sky color and polarization.

Likes JT's explanation of sky's blue color. Has difficulty with JT's explanation of polarization of skylight. Comments on absorptive powers of vapor and liquid.

Thanks for lectures on heat motion theory and radiation through earth's atmosphere, and for brochure on 'conformation' of the Alps. Asks about upcoming lecture of JH's son [Alexander].

Remarks on upcoming lecture of JH's son [Alexander], and on glacial movement.

Thanks for a gift.

Thanks for and comments on papers on scientific history and molecular physics, particularly on a magnetic experiment and on dynamical efficiency of coal relative to motion theory of light and heat. Comments on nature of heat, 'vis viva.' Deplores laxity with which physicists use and confuse terms 'force,' 'motion,' and 'energy.'

Regrets 'stupidity' of Italian post office, which lost note sent to JH suggesting reprinting of passage from Treatise Astr. of 1833 on operations of sun in second edition of JT's book. Also wants to publish JT's 'extremely philosophical views' on muscle contraction.

Thanks for and comments on paper on luminous and obscure radiation, particularly on extra spectral rays, incandescence of platinum, and experiment using transcalescence of iodine.

Is not 'at liberty' to speak of experiments on change of refrangibility of 'extra-red' rays. Discusses other experiments on extra-red regions, having used various prisms but not obtaining JH's results.

Surprised that JT cannot obtain heat spots [see JT's 1864-11-14]. Describes glasses and lenses used.

JT does not have 'luxury' of using sunshine; uses electric light. Perhaps this adds to inability to obtain heat spots [see JH's 1864-11-16].