These volumes are supplemented by the indexes contained in some of the letterbooks of GO25; taking them into account, the period for which indexes to outward despatches exist extends from July, 1836 to June, 1843, and the gap from 1848 to 1877 is closed.
In the first of the indexes in this series the entries are arranged alphabetically by year, the tabulation being: number of despatch, key-word of entry, sub-entry summarising the subject, date of despatch and reference to the page in the appropriate volume of GO25 ("vol. 1" now being GO25/15). This index deteriorates in its comprehensiveness as it proceeds.
The second index arranges the entries by initial only, in chronological sequence. It relates to part of GO25/23. Cross references are included, and the index in general is more useful than the first; both suffer from the limitation of the entries for any one despatch.