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.
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.
Forwards letter concerning 'solar bright particles' by W. R. Dawes. Inquires if diagonal solar eyepiece used in JH's solar spectrum observations.
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.
Richard Hodgson claims to have invented the diagonal solar eyepiece despite JH's description of it in Cape Results.
Cites quotation from Cape Results proving that JH invented the diagonal solar eyepiece. Discusses RH's claim. Note to JH accompanies this letter.
Compares W. L. Newman's and CP's calculations of optical coefficients to those in JH's work. Sends JH formulae and tables for calculating telescopic lens thickness and shape in relation to the dimensions of the telescope. Wishes JH luck on Iliad.
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.
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.
Thanks JH for solar observations. Discusses 'willow leaves' observations made at Greenwich Observatory after following JH's suggestions for solar eyepiece.
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 pursues claim to invention of the diagonal solar eyepiece while claiming that JH disclaimed the invention.
Compares JH's equation for lens curvature with that of C. F. Gauss.
Asks if JH still considering editing William Herschel's R.S.P.T. publications. Suggests that Alexander Herschel edit the work. Speculates that William Herschel observed the 'willow leaves.' JH's star catalogue will be printed by the R.A.S.
Gratitude for JH's gift of Caroline Herschel's autograph manuscripts to R.A.S.