Supports the remeasurement of N. L. Lacaille's geodetic arc in South Africa, giving a number of reasons for his support.

A note to accompany some letters being returned to GA.

Comments on the operational and organizational details of the magnetic and meteorological observatories, and on the supervisory committee's [the Physical Committee of the R.S.L.] responsibilities.

Recounts details of his recent visit to England. Recent astronomical observations. Has JH heard from C. K. J. Bunsen about his award?

Remarks on the significant increase in brightness of the star Eta Cygni, and comments on several other variable stars.

Sending a letter via Ca'colia Gibson raising various queries regarding nebulae.

Extensive letter answering the many queries about nebulae raised by AH in his 1844-4-18 [letter contains notes made by AH].

Sending the first volume of Kosmos. Queries regarding the Magellanic Clouds.

Sends thanks and very high praise for AH's first volume of Kosmos. Also comments on a number of other astronomical matters.

Mother and baby [Margaret and Julia] are doing well; JH asks questions relating to the Grovers giving up the lease on JH's property at Slough.

Convey his thanks to the King for the Order of Merit. Regrets he did not see the King or AH when they visited London recently. Gives astronomical information.

Would like JH's account of his own method of fixing a photograph as noted in his memoir. Singular phenomenon of the Daguerreotype. Hopes to produce a photographic paper to equal the silver plate before the month has expired. Will let him know when his process is complete.

Comments on JD's work in photography; JH goes on to talk about JH's ideas of 'chemical' rays of light.

Exchanging further information on several aspects of the photographic process [see RH's 1840-4-15].

Is grateful for the handsome manner in which JH has acknowledged RH's work. Would be willing to prepare a memoir for the R.S.L. Does Louis Daguerre's patent affect RH's manufacture of photographic papers? Has not studied the bromnets so far, but has studied the effects of bromine on plates. Comments on his results.

Sends his paper for communication to the R.S.L. Will send some more examples later as his camera has developed a defect.

Returns the photographic drawings of W. H. Fox Talbot with many thanks. Fears for their permanence. Has produced similar pictures himself acting on bromide of silver with hydrocholoric acid. Has had trouble with his periscope lens.

Was gratified to receive his memoir and to find many of his doubts corrected by JH's experiments. Hoped to enclose some sulphuretted papers but the chemicals went astray in the post. Intends to follow JH's example and precipitate a glass.

Is grateful for the suggested emendations to his paper. Comments on the action of iodine on silver and its oxide. When can he expect publication of his paper? Has noted a peculiar property in the calorific rays when copying engravings. Encloses some Daguerreotype papers.

Is grateful for referring him to Capt. Ludlow. Has now moved himself to Falmouth. What does JH think of the chances of success of a popular book on photography? He is contemplating the idea. Hears that J. B. Biot considers the production of colored drawings impossible, but is not convinced himself. Encloses description and drawing of a very clever instrument.