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Sends thanks and congratulations for paper verifying electric origins of all magnetism. Will give JF an actinometer with complete instructions. Includes some instructions for obtaining and using it. Sends regards to Mario Gemellaro, should JF go to Catania.
Suggests that JF use his instruments to compare the force of solar radiation at high and low elevations. Delineates possible methods for this experimentation, and lists results of similar experiments. Includes further information on the actinometer.
Gives JF permission to use JH's letter to JF's brother in any way JF sees fit to obtain the Chair of Natural Philosophy (at Edinburgh), but still does not wish directly to promote JF's selection. Briefly discusses results of JF's experiments with the actinometer.
Is drawing up a new actinometer and comments on JF's ideas about it. Encloses a letter to JF's brother.
Congratulates JF on obtaining, after some difficulty, the Chair of Natural Philosophy at Edinburgh. Accepts offer to discuss meteorology with JF's relation Leslie Melville[?], and hopes to mention his actinometer.
Offers JF advice about the telescope mirror [?] and looks forward to seeing JF on his way to France.
Wishes JF well in [Edinburgh] and leaves addresses where JH may be reached [at the Cape].
Discusses reduction of barometric observations. Praises the Cape's climate.
Discusses methods of magnetic observation, JH's actinometric readings in the Cape, and the need for more physical observatories.
Thanks JF for papers and requests copies of those JH has borrowed; comments on JH's observations on solar heat, light, and lines in spectra.
Discusses prospects for meteorological committee of B.A.A.S., on which they both will serve. Lacks time for it. Does not need hourly observations made by Committee of Physico-Mathematical Society of Edinburgh.
Writes 'in haste' to thank JF for a pair of papers. Comments on Louis Daguerre's pictures in Paris.
Outlines theory behind and method for preparing thermographic paper, which allows observers to determine 'what share each ray of the spectrum bears in producing the observed total effects.'
On the preparation of paper to exhibit a thermal spectrum.
R.S.L. will deviate from its intellectual purpose whenever it meddles in practical observations. Proper role for R.S.L. is to suggest goals and methods and to reward discoveries. Recommends discontinuing meteorological observations at Somerset House; other stations now provide better data. If R.S.L. insists on establishing a meteorological register, JH suggests one like that of J. F. Daniell.
Explains efforts at using a makeshift apparatus for 'fixing the spectrum.' Discusses current confusion and ultimate hope surrounding JF's meteorological recommendations. In a postscript, notes observations of meteors in Persei.
Instructions for preparing liquid for the actinometer. Describes 'very strange' experiments on the spectrum as well as an 'unusual' cloud formation.
Proposes meeting times in town. Suggests that JF observe the upcoming total eclipse astronomically. Agrees with JF's seemingly 'cold &c' circular on scientific partnerships, while regretting that it needed to be written.