Which percussion instrument originally required the player to turn a handle to adjust the tension of the drum head?

The instrument you're referring to is the "timpani," also known as kettledrums. Originally, players would turn a handle or use a pedal mechanism to adjust the tension of the drum head, allowing for precise pitch control. This feature is crucial for tuning the timpani to different musical keys during a performance. Modern timpani often use a foot pedal system for easier and quicker adjustments.