Sends the formula for finding the maximum diameter of the planets.
Sends the formula for finding the maximum diameter of the planets.
Asks for the use of an invariable pendulum and a clock from the Board of Longitude so that G. B. Airy and William Whewell can carry out experiments to measure the change in gravity and the mean density of the earth, in a Yorkshire coal mine.
Informs HK that JH intends to resign as secretary of the R.S.L.
Regrets JH's resignation as secretary of R.S.L.
Thanks HK for a chronometer, and sends some polishing papers.
Comments on a paper about differential calculus, prepared by Mr. Knight, which JH confesses he does not understand. Adds some astronomical observations JH made at Slough before leaving there, and noting the appearance of J. F. Encke's Berlin Ephemeris concludes with 'England is fated to lag in the rear of all her neighbours—at least in science.'
Collecting English observations of eclipse of 7 Sept. 1820 for H. J. Walbeck. Construction of object glasses.
Delivered R.S.L. resolution on 'Junction of French & English triangles' to François Arago. Arago alone will meet HK and T. F. Colby to finish triangles this summer. J. B. Biot will collaborate next year with HK on pendulum measurements.
Encloses JH's translation of J. J. Littrow's method of determining latitude by pole star. It already appeared in F. X. Zach's Correspondance astronomique.... Send Francis Beaufort's survey of Karamania coast.
Sends set of William Herschel's duplicated papers. Curious results 'examining the rings,' but bad weather has hampered experiments. Correction of spherical aberration. JH is using J. d'Alembert's Opuscules. Image of Alpha Lyrae.
Leaving town for a week. Will read [Francis Beaufort's] book after return. Delighted by 'two instances of good fortune' in one week at Union Place [HK's home].
Examine reflecting theodolite by [?] Schenk, now at Edward Troughton's. Arrangements for Madeira expedition. James South is willing to make observations there. 'Bowdich (the African)' is now at Teneriffe or Madeira and needs employment. William Herschel's health.
Encloses table of star declinations for 1815 and 1820, received from F. W. Bessel, who used different meridian circles for each year.
Thomas Young approved supplying [Richard] Copeland with two sextants and one mountain barometer.
'Our micrometer screws' are not in error. F. G. W. Struve's star measurements using Josef Fraunhofer's repeating micrometer agree well with JH's. So error must be in HK's observations.
Invites HK to dinner Saturday to meet James South and Alexis Bouvard.
Laments indiscretion of R.S.L. president [Davies Gilbert], attributing to JH statements JH never made about astronomical observations and James South's telescope. Clarifies what JH actually saw.
Misplaced papers are now found. HK must be 'first authority' on scale constructed for Wilhelm Struve. JH improved telescope by separating eyepiece lenses. JH's new baby girl.
F. G. W. Struve will arrive in July. Before HK and wife leave for Continent next week, please leave directions how Struve may obtain Struve's scale.
Shocked to read in paper of HK's loss. Offers condolences.