In 1818 rotary valves were introduced by Heinrich Stölzel and Friedrich Blümel (later, in 1839, piston valves were applied to the horn by François Périnet),[4] initially to overcome problems associated with changing crooks during a performance. Valves' unreliability, musical taste, and players' distrust, among other reasons, slowed their adoption into mainstream. Many traditional conservatories and players refused to use them at first, claiming that the valveless horn, or natural horn, was a better instrument. Some musicians, specializing in period instruments, still use a natural horn when playing in original performance styles, seeking to recapture the sound and tenor in which an older piece was written