On May 23, 1868 — In a battle of the top two Cincinnati teams‚ the Red Stockings cut down the Buckeyes‚ 28 – 10. Asa Brainard‚ from the Excelsior Club‚ makes his first appearance with the Reds as a number of players have changed teams this year. Those who do so while having a valid contract with their original team are called “revolvers.”
Source:
Baseball Reference May 23