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].

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.'

Thanks for lecture on glacier cleavage. Wonders how 'regelation' occurs when two masses of ice at 32° are placed in contact.

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

JT's paper on polarization of sky light suggests that neutral points are functions of cloud density. This verifies JH's earlier explanation of blue sky color. Incomplete polarization. Cause of blue color in water. Corrects note on W. A. Miller's observations of rainbows.

Is studying vesicles. JH's son [Alexander] may yet get Royal School of Mines appointment.

Asks JH to keep memoirs JT sent with regard to JT's application for position at University of Sydney.

Asks whether Michael Faraday's work with glass resulted in improved manufacturing or if rather its main scientific value was in discovery of diamagnetism.

Comments on excellence of the lecture at the Royal Institution of JH's son [Alexander].

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

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.

Remarks on physical properties of ice and their bearing on glacial phenomena. Asks for help inventing term for idea of 'fracture and renewal' of glacial bendings.

Asks JH to be a shareholder in venture to publish new weekly scientific journal.

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

Thanks for JH's suggestions on JT's outline of comet speculations. [G. B.] Airy, too, has replied. Includes more speculations on 'envelopes' and nucleus of comet.

Sends copy of JT's '3rd Memoir,' along with specimens of liquid mercury ethyl and mercury methyl from discoverers Edward Frankland and B. F. Duppa.

Continues experiments with carbonic acid and electric light [see JT's 1868-11-30], suggesting possible cause of blue cloud color and eventual whitening of light.

Asks JH to review paper on blue color of sky, polarization of skylight, and polarization of light by cloudy matter.

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.

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.'