Electro-telegraphic longitude operations executed during the years 1875-77 and 1880-81 /
Campbell, William Maxwell,1839-
Heaviside, William James,1840-
Survey of India.Trigonometrical Branch.
Dehra Dun : Office of the Trigonometrical Branch, Survey of India,
1883.
India. Great Trigonometrical Survey.
Longitude
Longitude
Longitude