Colonel Charles Henry Dudley Ryder (1868–1945) was a distinguished British Army officer and explorer who served as the Surveyor General of India from 1919 to 1924, a role based in Calcutta.

The second edition includes additions such as the magnetic declination. Scarce, with only 2 copies of this edition in UK institutions (Cambridge and Oxford), and not in BL.

Second edition; heliozincographed colour map, dissected and mounted on linen in 36 segments, scale 1 inch to the mile, full size 69 x 105 cm, folding into original blue cloth-backed boards with gilt lettering, a very good copy.