The Letter Books contain copies of outgoing correspondence from the Secretary to missionaries (mainly the mission secretary).

Letter to Rev R Eteson regarding his good work preaching in the Bazaar and the surrounding villages, letter to Rev Lathy re the return of Rev M Wilkinson and his family after time spent in England; letters to Rev F Wybrow, Rev J Innes and Rev J F Osborne. There are also many letters of instructions to new missionaries going out to India such as Rev W Smith, Rev W Morse, Rev J C G Knorpp, Rev C B Leupolt, Rev J Haberlin and Rev J T Lincke. The Secretary advises self-denial and not to expect too much success in the first few years.