Resolved puzzle about sidereal year, which needs better definition. Error between true and nominal positions prevents TY adopting 'equinoctial time' for chronology investigations.

J. J. Littrow's paper in F. X. von Zach's April [Correspondence astronomique, géologique, hydrographique et statistique] is only 'a new hash' of [F. W.] Bessel and no improvement.

Send plan of furnace to TY or Michael Faraday before tomorrow's committee meeting.

Invites HK to dinner Saturday to meet James South and Alexis Bouvard.

Asks questions about the prospectus [see JE's 1826-3-2] prepared by the Berlin Royal Academy for a map of the heavens. Asks JE to send JH a copy of [K. L.] Harding's star atlas.

Reports on interest at the Astronomical Society, especially of [Thomas J.] Hussey, in the plan of the Berlin Academy for a new star chart. JH cannot participate due to JH's commitment to re-examine his father's nebulae, which requires that JH reside far from London.

Encloses an outline of JH's paper on iron [? 'On the Separation of Iron from Other Metals,' RSPT (1821), 293-9].

[Responding to WT's 1826-2-7], JH thanks WT for materials sent, makes suggestions regarding WT's upcoming trip to Geneva, and asks WT to deliver a book to [Alfred] Gautier.

[Responding to WT's 1826-3-24], JH concurs with P. S. Laplace's view about the advantage of astronomical observation from high elevations, e.g., from mountains. Comments on telescope prices, a paper by WT, Florence, and JH's plan to visit the Continent.

Thanks WT for bringing to JH Josef Fraunhofer's publications and Franz Gruithuisen's plates. Recounts JH's geologizing in France and JH's efforts to measure solar radiation.

Describes plan to carry out pendulum experiments with G. B. Airy. Asks JH for help in borrowing instruments from the R.S.L.

Describes the pendulum experiments he and G. B. Airy are carrying out in Dolcoath Mine.

Reports that an accident destroyed one of the pendulums used by G. B. Airy and WW in their Dolcoath experiments. Obtained some results and believes in the general soundness of the method employed.

Asks WW to watch over the printing of JH's 'Light' for the Encyclopaedia Metropolitana. Describes that work as not especially original and as free of historical information. Discusses JH's trip to Calais.

Tells JH that the Lucasian Professorship has become available. Believes most Cambridge people favor JH. Urges JH to write the electors, i.e., the heads of the Cambridge colleges.

Declines to become a candidate for the Lucasian professorship. Explains his reasons. Has written in support of Charles Babbage. Thanks WW for seeing JH's 'Light' through the press. Describes JH's travels on the continent, including his 'geologising.'

Hopes that JH will visit Ireland and if he does that he will visit them. David Brewster also intends visiting Ireland.

Thanks for ME's letter; JH hopes to see her in Ireland in summer.

Berlin Academy plans a new Astronomical Chart. Thanks for JH's work on the double stars. Will see he has changed his address.

Regrets he has taken so long to answer his letter. Gives reasons why the Commission does not allocate the same zone to two astronomers. Readings of J. Grooby and T. J. Hussey. Thanks for JH's work. J. E. Bode's work will be continued.