Gustavus Hinrichs is also a [not highly regarded] correspondent of JT’s; he will put GH’s papers on the table at Royal Institution to ease CD’s conscience.

Dined with the Asa Grays at Hooker’s. Told Mrs Gray that CD’s ill health was a benefit because it caused him to ponder a great deal.

No summary available.

No summary available.

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

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].

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.

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.'

Corrects misinformation about refraction and dispersion of mercury ethyl and mercury methyl.

JT has suggested that JH's son [Alexander] be appointed to position in Royal School of Mines, but colleagues, unwisely, JT thinks, want someone more well-known.

Continues experiments with carbonic acid and electric light [see JT's 1868-11-30], hoping to 'explode' idea that atmosphere's polarization is due to reflection by air particles.

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.

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