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.
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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.
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.
Writing to welcome JH home from the Cape.
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.
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.'
More about paper being published in both the R.S.P.T. and Athenaeum.
Questions JH's intent to display 'photogenic drawings' to R.S.L.
Wants to withhold description of 'developing' process until it is perfected to obviate others using it. Also refers to second process to make 'positive' and 'negative.'
Some comments on JH's light and photography experiments, especially effects of different kinds of glass and fixing with ferrocyanate.
Describes mediocre results obtained using ferrocyanate of potash for fixing image. Mentions some other methods, including his favorite, common salt. Asks JH to keep these secret.
Finally had success washing with ferrocyanate. Wants to present note of 'his' processes to R.S.L. and so to the world.
Wishes to communicate to J. B. Biot, and so to Academie des sciences, JH's two 'beautiful' fixing methods, by hyposulfite and ferrocyanate.
Enlarges upon his method of using salt as photographic fixer; then asks JH to explain the chemistry thereof. Has tried Louis Daguerre's fixing process without success.