Account of the Great Trigonometrical Survey of India Volume XVII. Electro-Telegraphic Longitude Operations executed during the years 1894-95-96. The Indo-European Arcs from Karachi to Greenwich. Prepared under the directions of Major S. G. Burrard. Survey of India. Geography,India,Map

First edition. 4to. pp. xvii, 320, 3 (list of Survey publications); port. frontis. of J. T. Walker, 5 plates of instruments, one folding diagram, two engraved maps, one large folding map of India; loosely inserted errata and corigenda; light water-marking to three plates at rear, paper adhesion to flyleaf, else very good in the original cloth gilt. The Survey of India, the project to map India and adjoining regions, was initiated in 1802; its work continues today. Based at Dehra Dun, in the foothills of the Himalaya, the programme successively mapped the subcontinent. In the 1890s, in order to coordinate the findings with the similar survey of Britain, a secondary project was undertaken to determine the longitude between Karachi and Greenwich. The work was facilitated by taking transit readings of stars at different locations connected by telegraph: Karachi, Bushire and Jask (on the Persian Gulf), Tehran, Potsdam, and Greenwich. The present volume of the Survey of India reproduces, in table form, these observations, prefaced by chapters on the background to the survey, the choice of observation stations, methodology etc. The two engraved maps show the schematic connections between Greenwich and Karachi, and the arcs of Eurasia; the large folding map is an index chart to the Great Trigonometrical Survey showing the triangulation of India.