1879 Vol 2 History and Description of Principal Triangulation and its Reduction by Walker s.pdf 42.64 MB
1886 Vol 4A Principal Triangulation of Jodhpore and Eastern Sind of NW Quadrilateral by Haig s.pdf 16.63 MB
1893 Vol 15 Electro-Telegraphic Longitude Operations 1885-92 and final results by Strahan s.pdf 28.53 MB