Sub-sub-series consists of indexes to the registers of letters received (Department of Public Works fonds, MIKAN 22 (RG 11), Vol. 739 and p. 24 herein) until December 1892 and, commencing in January 1893, general indexes to correspondence received in the branch to about 1910.
Volumes 1271-1273 provide the name of the correspondent and a letter number; no date or subject is given. The letter number serves as a cross- reference to the appropriate register of letters received, where more detailed information concerning the correspondence is located.
Volumes 1274 and 1792-1793 were compiled on the same basis, however there are no registers of letters received for the period 1893-1910. These volumes provide the name of the correspondent, the letter number, and in some instances, a file reference, especially for correspondence received after 1906 when the Canal Branch adopted a system of numbered subject files. Unfortunately, there is no way of linking the letter number to the actual documents. Files that have survived form part of MIKAN 134579 (RG43-B-I-1), Vols. 1282-1735.