Signing certificates for election to fellowship in the R.S.L. at this time [JH having been nominated for President] would be very awkward for JH, so he will not sign for WT.

Asks about rumor regarding JH going to Cape. Describes some electrical experiments WT saw at Royal Institution and refers to some WT carried out years earlier.

Asks for seeds and roots of native plants of the Cape. Refers to JH's writings on beating of the heart and comments on some optical experiments of Charles Wheatstone and David Brewster.

Comments on JH's paper on potash in Annales de chimie. Has observed reaction products in microscope. Concerned over delay in publication by David Brewster of his experimental results in optics and light, especially as WT not convinced of legitimacy of rumored results.

Has performed some Newton's rings interference experiments. Asks whether such experiments have already been communicated to the R.S.L.

Trying to understand David Brewster's results on absorption of light in gaseous state, and the dark lines in solar spectrum, the cause of which he misunderstands.

Sending WT some seeds. Had hoped to send some bulbs.

Is sending WT some botanical specimens through Andrew Smith, whose scientific abilities JH praises. Asks WT to assist Smith in England. Encourages WT's work in mathematics and in 'photology.' Reports on JH's astronomical observations and theorizes about sunspots.

About plant seeds sent by JH from the Cape, WT having sent him some Mexican seeds in return. Halley's Comet only clearly seen on two nights.

Thanks for specimens of [light] 'sensitive paper.' Praises it. JH has handed over all his specimens of photography to R.S.L. Recommends a paper by the chemist Henri Regnault.

Thanks for photographic specimens WT sent. Reports on JH's recent experiments, including some using lenses, in photography; comments on WT's experiments and on the process of patenting.

Writing to welcome JH home from the Cape.

Says that for the next four to five months will be in residence at 10 Hanover Crescent, Regent's Park. Offers various botanical specimens to WT, including a Satyrium named after JH. Mentions Eta Argus. Believes the 'Southern Sky has been pretty well rummaged.'

About Cape bulbs and seeds, the new travel by railway from Slough to London, and concern about interest in animal magnetism.

Thanks for more Cape bulbs.

Will give a paper on fixing the image formed by the camera obscura to R.S.L. and wants to review it with JH first.

[Responding to WT's 1839-1-25], JH reports that he cannot come to London to see WT's 'curious process of fixing the image formed by a Camera obscura.' Invites WT to come to Slough.

JH is indisposed, so WT will come to Slough to review paper [see WT's 1839-1-25]. Asks JH about appropriate curve on lenses for camera obscura for 2-foot focus.

Has received urgent request from Athenaeum to allow them to publish paper on 'Photogenic Drawing' before it is read to R.S.L. in light of announcement of the 'Parisian invention.'

[Responding to WT's 1839-1-29], urges WT to find some way of giving at least slightly different papers to R.S.L. and Athenaeum. Comments on process of fixing image, referring to a trial of his own.