Introduces Dionysius Lardner, author of system of algebraic geometry, visiting England.

Received volume on double stars by JH and James South. Followed JH's advice, ordered instruments from Germany. Asked Josef Fraunhofer to design transit instrument to fit pillars designed by Edward Troughton. Quotes Fraunhofer's response [in French] that pillars should be moved to accommodate his instrument. David Brewster anxious for JH to answer last letter.

Appreciates JH's interest in and encouragement of CW's experiments. Describes new experiments to elucidate theory of undulatory motion of sound and light. Invented 'kaleidophone' to display paths of vibrating rods. Hopes JH can confirm these results.

Sends drawings associated with WW's paper and passed by [R.S.L.] Council for printing, and memoir from M. A. Pictet.

Invites JH to dinner Saturday to meet J. G. S. Van Breda.

Encloses paper sent by Mr. Perkins for R.S.L, and impression just received from printer.

Returning to Cookham. Thanks for minerals. Describes shipment of new minerals from Baffin Bay. Expecting another from Rio de la Plata, courtesy of Woodbine Parish [consul-general to Buenos Aires].

Ask Charles Babbage to send tables of logarithms to TY, who will compare them to [Brook] Taylor's. Bets that five errors will be found. Did JH order mountain barometer from [J. F.] Newman? Will inquire about [W. E.] Parry's instruments. Admiralty, not us, should order sextants.

Questions JH's conclusion that Board of Longitude has power to interfere in Admiralty operations. Disagrees that Nautical Almanac errors are serious. Compares them to tables of Charles Hutton, F. X. von Zach, and H. C. Schumacher. When will TY receive Charles Babbage's table?

Invites JH to dinner. Expects Mr. and Mrs. [Andrew?] Spottiswoode and Mr. and Mrs. Beckwith.

[Board of Longitude] must answer to Parliament, not to public opinion. Do not contest the system. Order pocket sextants; they and barometer will be sent to Captain [Richard] Copeland. Knows how JH feels about expenses sent to Edward Sabine, but please write receipt and send it to TY within week. Will write directly to Charles Babbage for tables.

Suggests change in JH's table of refractions. Possible error in John Pond's reductions [illustration].

Comments on a variety of topics about various scientific persons on the Continent, on JH's travels in Europe, on ways to send packets between England and Europe, and on FZ's copy of the Nautical Almanac, which FZ has not yet received. Makes comparisons between his and JH's barometer, offers some comet observations, and talks about the appropriate date for Easter. Awaits JH's double star observations.

Reports on some observations from JS's observatory near Paris and on his contacts with the Paris Observatory. Relays to JH a request from Alexander von Humboldt for barometric observations. Invites JH to visit.

On the eloges of William Herschel being prepared by François Arago and J. B. Fourier. JH's and JS's work on double stars much appreciated among French astronomers. On Alexis Bouvard, Arago, and other French astronomers. On Wilhelm Struve's observations of double stars.

On the transmission of materials between JH and JS. On their joint observations.

Has been making observations as JH requested of the star 70 Ophiuchi. Argues for the accuracy of observations of double stars that JH and JS have made.

Is sending materials to JH. Reports on continued efforts to observe the star 70 Ophiuchi. Has sighted three nebulae that may be unknown to JH.

If you can send a copy of our paper on double stars immediately, it seems certain that the Academy will award a medal for it. Informs JH of most expeditious method of sending same.

Has returned from London. A preprint of JS's and JH's paper on double stars has been delivered to François Arago. Is finding many errata in their paper. Has received a letter from Josef Fraunhofer and the paper [on double stars] of Wilhelm Struve.