Further details about exhibiting samples of the South African meteorite [see GD's 1864-1-3]. [Letter illegible in parts.]
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Further details about exhibiting samples of the South African meteorite [see GD's 1864-1-3]. [Letter illegible in parts.]
Has received a letter from Angelo Secchi who states that he has seen James Nasmyth's 'willow leaves.' Remainder of letter relates to the JH prism, which he sent him through Cardinal N. P. S. Wiseman.
Sent JH 'Index Chart' of Great Trigonometrical Survey of India. Compares five triangulation methods: longitudinal series, George Everest's, G. B. Airy's, that of JH's son John, and minimum squares. JH's son and bride avoided cyclone that destroyed Calcutta Observatory.
Indian Triangulation chart showed progress to May 1862. Explains why arcs of meridians and parallels were chosen over diagonal braces. G. B. Airy's method of determining errors helped. Will take note and package from Maria [Herschel] to JH's son John.
Sending a weather almanac by a person called Orlando Whistlecroft. Comments on his weather forecasting.