From:
James Thomas Walker
To:
Sir John Herschel
Date:
[15 December 1864]
Source of text:
RS:HS 18.17
Summary:
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.
Contributor:
John Herschel Project