Pleased JH liked his paper on differential photometer. Discusses apparatus for experiments on light. Describes some papers he has written and some he is writing.

Comments on ES's measurement [in his Account of Experiments to Determine the Figure of the Earth] indicating 'the increase of the fraction expressing the earth's compression.' Predicts that ES's result will cause a 'sensation,' but does not commit himself to it.

Responds to ES's proposal to conduct a series of meteorological observations from the peak of Teneriffe. Promises to bring it before the Board of Longitude for consideration for support.

Clarifies issues discussed in an earlier letter. Discusses whether the project of making meteorological observations will be feasible if the Board of Longitude does not offer financial support. Attempts to arrange a meeting with JH.

Responds to ES's letter of 1825-4-4, stating that JH now understands that ES will proceed with the Teneriffe observations only if funds are provided. Praises Sabine's previous work.

Shares JH's doubts whether the Board of Longitude will fund the Teneriffe expedition, the importance of which he again stresses. Cannot personally cover the costs. Thanks JH for his support and praise.

On 1825-4-7 presented ES's proposal for experiments at Teneriffe to the Board of Longitude, which judged the experiments not sufficiently relevant to the Board's concerns. Offers to seek endorsement from the R.S.L.

Encourages JH to bring ES's proposal for Teneriffe experiments before the R.S.L. Council.

Invites ES to join him and other scientists for dinner. Requests that ES prepare a detailed description and justification of his proposed Teneriffe experiments for consideration by the R.S.L. Council.

Read your proposal on experiments at Teneriffe to the R.S.L. Council, which declined to make 'an especial recommendation' in support of them to the government.

Six artillery men have been placed under ES's command. Encloses letters from Charles Bonne. Asks ES to oversee the arrival of 180 rockets to be used at Wrotham and Fairlight. Proposes that ES test whether a light at Wrotham can be seen at Fairlight in which case gunpowder will be used instead of rockets. Sets date for ES to meet Bonne in Hornoy. Urges ES to record his expenses for the Board of Longitude.

Clarifies that the six artillery men are at ES's disposal but under JH's command. Agrees to oversee arrival of the rockets. If expenses are to be paid by the Department of Ordinance, a request must be made by the Secretary of the Board of Longitude. Agrees to keep a record of expenses, not including his time spent, which he considers 'public service.'

Reports on his meeting with Charles Bonne and their subsequent failure to see any signals the first night from either Mont Javoul or La Canche. Worries that the distances are too great for measurements so close to the sea. Speaks of similar measurements between Paris and Strasburg.

Reports his 'entire failure' with Charles Bonne to see signals from both La Canche and Mont Javoul on the same night. Tells of moving the telescopes to Tuniers on 1825-7-15. Speaks of similar experiments elsewhere, which also failed. Concludes that distance is not the only factor in distinguishing signals. Plans to visit JH on 1825-7-25.

Reports Charles Bonne's voyage to Mont Javoul and discovery that the rockets there had been sent off too early, accounting for the previous failures. Reports subsequent successes. Conveys his plans to arrive at Teneriffe.

An account of the rocket experiments and P. S. Laplace's letter will be left at the R.S.L. Finds in Laplace's letter encouragement for the corroboration regarding the measurement of latitudinal degrees. Dismisses Laplace's opinions that the climate of Spitzbergen is too unfavorable for experimentation and expounds on the many reasons to favor this town.

Acknowledges receipt of WS's second volume of observations and the new telescope's results. Mentions Caroline Herschel's catalogue of nebulae.

Thanks profusely for two volumes of Astronomical Society's memoirs. Sends brochure containing two memoirs: one on eclipse of 1820, the other on two comets in 1823-24. Gives news of various acquaintances and friends.

Asks WS for account of the performance of his new [Josef] Fraunhofer telescope. Corroborates WS's double star motion data, except for 70 Ophiuchi, where JH and [James] South find no motion. Asks for observational targets and urges care in WS's observational technique. Mentions WS's intention to undertake celestial zone with [F. W.] Bessel. Describes [Henry] Kater's 'floating collimator.'

Illegible.