 After securing sole-ownership rights in December 1816, Constable began work on a supplement to the 5th edition, even before the fifth edition had been released (1817).The supplement was completed in April 1824, consisting of 6 volumes with 4933 pages, 125 plates, 9 maps, 3 "dissertations" and 160 biographies, mainly of people who had died within the preceding 30 years.This supplement contained a rudimentary form of an index, listing the 669 articles in alphabetical order at the end of volume six, by volume but not page number, but it did not contain any sort of cross referencing.