To the Senate of the United States:
It having been represented to me by persons whose statements and opinions were thought worthy of confidence that the trade of the United States might be extended and rendered more lucrative by commercial arrangements with the countries bordering on the Indian Ocean, and being informed that the success of any efforts which might be made to accomplish that object would materially depend upon the secrecy with which they should be conducted, I appointed Mr. Edmund Roberts a special agent of this Government for the purpose of visiting those seas and concluding such commercial conventions as might have the effect of securing additional advantages to our trade in that quarter. This agency has resulted in the conclusion of treaties with the King of Siam and the Sultan of Muscat, whereby the commerce of the United States with the countries subject to the dominion of those princes, which had been previously embarrassed by serious disadvantages and obstructions, is placed upon a footing with that of the most favored nation. These treaties, the former of which was signed at the city of Siayuthia (commonly called Bankok) on the 20th day of March, 1833, and the latter at the city of Muscat on the 21st day of September of the same year, are submitted to the Senate for their consideration and advice.
I transmit a copy of the instructions which were given to the special agent and a communication made by him to the Secretary of State, containing particular and important information respecting the countries with which these treaties have been concluded. The expenses of the agency have been defrayed out of the contingent fund for foreign intercourse.
Andrew Jackson, Special Message Online by Gerhard Peters and John T. Woolley, The American Presidency Project https://www.presidency.ucsb.edu/node/201082