Is anxious for some means to be developed to get a measurable quantity [preferably by weight] from the action of a beam of light on a surface. JH has been experimenting in photography with 'flouric' compounds.
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The Sir John Herschel Collection
The preparation of the print Calendar of the Correspondence of Sir John Herschel (Michael J. Crowe ed., David R. Dyck and James J. Kevin assoc. eds, Cambridge, England: Cambridge Univ. Press, 1998, viii + 828 pp) which was funded by the National Science Foundation, took ten years. It was accomplished by a team of seventeen professors, visiting scholars, graduate students, advanced undergraduates, and staff working at the University of Notre Dame.
The first online version of Calendar was created in 2009 by Dr Marvin Bolt and Steven Lucy, working at the Webster Institute of the Adler Planetarium, and it is that data that has now been reformatted for incorporation into Ɛpsilon.
Further information about Herschel, his correspondence, and the editorial method is available online here: http://historydb.adlerplanetarium.org/herschel/?p=intro
No texts of Herschel’s letters are currently available through Ɛpsilon.
Is anxious for some means to be developed to get a measurable quantity [preferably by weight] from the action of a beam of light on a surface. JH has been experimenting in photography with 'flouric' compounds.
Thanks for RH's paper on mineralogy. JH has explored use of mercury together with iron in photography.
Some information about Charles Piazzi Smyth. JH needs information about some of RH's photographic paper, which JH has tried but without success.
Believes that the operative rays in JH's thermographic process are neither 'calorific' nor 'thermal'.
Sends RH a packet of photographs with a description of each type.
Read John William Draper's papers; although he believes that Draper's instruments are inconsistent, JH feels that they are still important because they are measurable. Decries [L. F.] Moser's skepticism of photography's value, calling it a 'blindfolding to some of the most interesting physical relations that have ever been discovered.'
Sorry to hear RH has been ill; JH sends some photographic examples.