Dr David Richardson undertook a series of missions whilst Assistant Commissioner in the Tenasserim Provinces (including modern-day Thailand and Myanmar). This material includes some of his journal of his mission to Siam, and a report and letters to E.A. Blundell, Commissioner in the Tenasserim Provinces.

"Journal of a Mission from the Supreme Government of India to the Court of Siam" covering the dates 18 December 1838 - August 16th 1839. The Journal is incomplete. The journal gives accounts of the journey, the places at which Richardson stopped, and of his time in Bangkok. Not every day is represented in this account, and there are edits and annotations on the journal, possibly in a different hand.