The Rumford Medal was instituted in 1800. In that year it was presented to Benjamin Count Rumford, and in 1804 to John Leslie. These are the only two recipients before William Murdoch in 1806 (not 1808). It has been presented biennially since 1848; before that date the interval is somewhat irregular.
I am, yours truly
Asst. Sec. RS [Assistant Secretary, Royal Society]'.