From:
James Thomas Walker
To:
Sir John Herschel
Date:
[9 December 1864]
Source of text:
RS:HS 18.15
Summary:
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.
Contributor:
John Herschel Project