On August 30, 1913, St. Louis was playing in Cleveland in the third game of a four game series. In the bottom of the seventh, Rehmer and Ragsdale replaced Reis and Waring as the battery. Potts led off for Cleveland, beating out a bunt single that Ragsdale was too slow to field. The next batter, Patton, also bunted. Rehmer fielded it and threw to Kahl covering first, and Patton stepped on Kahl's hand as he went to field the ball. Kahl had to leave the game; he missed most of the rest of the season. Gaston moved from center field to take over at second base, Jones moved to center field from left field, and a player identified as Kempling replaced Jones in left field. The box score shows one at-bat for Kempling and zeros the rest of the way.
The following day, catcher Waring played left field while Jones covered center field and Gaston played second base. This was the final game of the series in Cleveland. On September 1, Murphy joined the club in Chicago and played third base, while Scott slid over to cover second base, and Gaston and Jones returned to their normal outfield positions.
The simple assumption is that Kempling is just a mis-indentification of Scott Kempin (identified as Kemplin in the boxscores in 1913). However, Kempin's last game with St. Louis was on June 3, aside from two pinch hitting appearances at home on June 9 and June 12. After he was released by the Terriers, he joined the semi-pro Alpen Braus. He appeared in a box score for that club in the St. Louis Globe-Democrat on August 11, and again on September 8. It is unlikely that he would have been with the club on their road trip. Further, if he had been with the club, he, and not Waring, likely would have played in left field on August 31, the day after Kahl was spiked.
It seems more likely the Kempling was a local player present at the game called upon to fill in after the injury to Kahl. The Terriers only had nine position players on the road trip at that time (two catchers plus one for each other position), so the only two plyers left on the bench for St. Louis were pitchers Kuepper and Bishop (the second catcher, Ragsdale, having already entered the game that inning). No player with that name appears in the Cleveland newspapers around that time, so Kempling is likely an alias. Absent a lucky break, I suspect that he will never be identified.
One intriging possiblity is Chester C. Kemp. Kemp was a catcher for Case Western Reserve in the spring of 1913, and by the fall of 1913 he was writing articles for the Sports section of the Cleveland Plain Dealer. Just days after Kempling played for the Terriers, Kemp was identified as the catcher for the Plain Dealer baseball club in an upcoming match (Plain Dealer, September 4, 1913, pg. 8). There is no evidence to support this hypothesis, but one could imagine he was at the game, either professionally or as a fan, and was called upon to take the field.