Notwithstanding its' original publication in 1904, it was found to employ "isometric" principles of muscle development, which were not identified as such until the 1980's!
Musicians of all levels and all instruments have reported rapid improvement in strength, flexibility and accuracy not generally obtained from the use of traditional instrumental exercises, such as repetitive scale practice, "Hanons", etc.
"The System" almost lost forever, has now been recovered and restored.
How good can you get? How fast? I invite you to try "The Original" Cowling System, and see!