Search: John Herschel Project in contributor 
Herschel, John in correspondent 
Walker, James Thomas in correspondent 
Sorted by:

Showing 16 of 6 items

From:
Sir John Herschel
To:
James Thomas Walker
Date:
[24 December 1863]
Source of text:
RS:HS 18.12
Summary:

Received tables of heights recorded in 'Sind, the Punjab, N.W. Provinces, and Central Asia.' Sees scientific interest in JW's described effect of refraction on levelling. Work is important to irrigation.

Contributor:
John Herschel Project
From:
James Thomas Walker
To:
Sir John Herschel
Date:
[2 January 1864]
Source of text:
RS:HS 18.13
Summary:

Received JH's two letters acknowledging receipt of 'Volume of Tables of Heights' of the Great Trigonometrical Survey of India. Hopes to visit JH and discuss phenomenon of terrestrial refraction. Received valuable assistance on tables from JH's son John.

Contributor:
John Herschel Project
From:
James Thomas Walker
To:
Sir John Herschel
Date:
[6 June 1864]
Source of text:
RS:HS 18.14
Summary:

Returned from Gloucestershire. Will visit Collingwood on Monday.

Contributor:
John Herschel Project
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
From:
Sir John Herschel
To:
James Thomas Walker
Date:
[10 December 1864]
Source of text:
RS:HS 18.16 (C: 24.77)
Summary:

Received Indian survey chart. JH's son John wrote of higher-order ellipsoidal triangles with sides based on geodesical triangles. JH objects that these violate principle of diagonal bracing. Proposes different triangles and names sites in India as apexes. Received G. B. Airy's paper on reduction.

Contributor:
John Herschel Project
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