As Surveyed in January 1856. Scale 1000 yards to the Inch. Joseph Obbard, River Surveyor. T. Black, Asiatic Lith: Press, No. 4, Waterloo Street, Calcutta.
As surveyed in May and June 1857. Scale of a thousand Yards to an Inch. Joseph Obbard, River Surveyor, H.C.S.V. Cavery, Diamond Harbour, 14 th June 1857. T. Black, Lithr:, 4 Waterloo St., Calcutta.