Experiments with lens curvature and prisms. Wants to discover set rules for lens thickness-to-curvature ratio.
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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.
Experiments with lens curvature and prisms. Wants to discover set rules for lens thickness-to-curvature ratio.
JH to visit CP's house. CP suggests they both visit J. P. Gassiot, where they might also meet with Michael Faraday. Asks JH if there are experiments he would like to see during visit. Reports observing Fraunhofer lines through a prism.
Looking forward to visit to Collingwood.
Congratulates JH and Margaret Herschel on birth of a daughter [Francisca?]. Asks JH's opinion of the ideas of 'lines of force' and 'lateral shakes.' Conducts a force experiment with J. P. Gassiot.
Receives object glass from Munich for double star observations.
Visits Angelo Secchi at Rome observatory, where they are comparing information in Cape Results to their observations.
Writes to JH to propose hiring JH's son Alexander for a year to work in CP's laboratory and make observations in CP's observatory.
Searches for asteroids. Measures double stars and variables; Alexander Herschel assists. Asks JH's opinion of parallax measuring methods. R.S.L. funds offered to M. J. Johnson's family in his memory.
Asks JH's opinion on CP's eclipse observations plans, especially on which equipment to use. Intends to use a 'diagonal solar eyepiece' during the eclipse. Plans to observe carefully and to sketch solar flares.
Sends observations of eclipse; asks JH to check accuracy. Details observations with diagonal solar eyepiece. Describes solar corona and lists bright stars visible during totality.
Problems making actinometer observations during solar eclipse. Reports he did not observe the supposed planet Vulcan, but a fixed star. Sends micrometer observations. Describes shape of prominences.
Observes and measures sunspots. Takes spectrum of solar photosphere; detects sodium and magnesium absorption lines. Pleased with Alexander Herschel's work on the solar spectrum; wishes he would begin work on stellar spectra.
Warren de La Rue observes 'willow leaves' [mottling on solar surface]. Diagonal solar eyepiece works with great success. Praises de La Rue's work as having astounding accuracy.
Describes debate at R.A.S. over the nature of the 'willow leaves.' Different parties argue that the 'leaves' are solid, precipitate, or non-luminous gas.
Thanks JH for solar observations. Discusses 'willow leaves' observations made at Greenwich Observatory after following JH's suggestions for solar eyepiece.
Gratitude for JH's gift of Caroline Herschel's autograph manuscripts to R.A.S.
Asks JH for information on the Beaufoy Clock owned by R.A.S., which is now missing. Requests JH to read R.A.S. Annual Report.
Thanks JH for reading R.A.S. records. G. P. Bond will not receive R.A.S. medal. The Beaufoy Clock is recovered.
Richard Hodgson claims to have invented the diagonal solar eyepiece despite JH's description of it in Cape Results.
Richard Hodgson pursues claim to invention of the diagonal solar eyepiece while claiming that JH disclaimed the invention.