Response to a letter from JH to G. G. Stokes [1867-5-5] seen by GA, on the problem of the effect of the telescope on illumination from a light source, especially related to a solar eclipse.

Is considering a new edition of Outlines Astr.[?] and wants to provide the latest determinations of the periods of rotation of the planets.

Comments on the state of William Whewell's health, and about the theories of E. F. W. Klinkerfüss [see JH's 1866-2-27].

Passes along a report that someone took a 4-foot telescope to the top of Snowdon [mountain], from where he could see the eight satellites of Saturn and the rings of Neptune.

Has received GA's paper on spectral lines and is amazed that it is possible to see a spectrum in the light from faint nebulae.

About observing a grain-shaped spot on the sun; greetings to Friedrich Winnecke.

Sends GA [see GA's 1863-11-21] JH's copy of the Melbourne telescope correspondence and reports; needs information from GA and Edwin Dunkin about the sun's motion, although JH questions some of Dunkin's work.

Urges JH to attend the next meeting of the Board of Visitors of the Royal Observatory, especially as GA believes some of the members of the Board do not understand the scientific problem [?].

Circular letter advising of the availability of back copies of various Royal Observatory printed observations.

As GA is about to leave on holiday, he brings JH up to date on the state of the nebula calculations [see JH's 1862-5-28].

Does JH need the original calculation sheets to deal with the errors in the nebula catalogue [see GA's 1863-2-23]?

Thanks GA for the papers sent; asks GA to review enclosed note on solar motion [see JH's 1863-11-22].

Returns JH's letter from G. G. Stokes about eclipse spectroscopy; GA has written to Stokes as well and encloses a copy of this letter.

Provides JH with best definition that GA has available for the gallon [see JH's 1867-11-3], noting that methods for establishing standards are revised, even if the standards supposedly are not.

Writes to acknowledge receipt of letter [see JH's 1864-11-25], but it will take time to work through JH's calculations carefully.

Thanks JH for his useful letter [see JH's 1867-12-2]; it will be of value to the Commission on Weights and Measures.

Thanks JH for his clear letter [see JH's 1867-12-3] about the pound weight standards.

Proposes a principle for the establishment of musical scales to satisfy musicians, not mathematicians, as JH had apparently done.

More on musical scales [see GA's 1868-4-3]; GA here proposes the use of hyperbolic logarithms to help establish the scales.

Comments on several nebulae, and on GA's receiving an honorary degree [from Cambridge University].