Bear with me while I describe this one...
In a very large circle, say about 80' in diameter, place metal tubes of varying lengths at various intervals along the circumference of the circle. These tubes would be hanging from thin wires attached to some sort of mounting structure. (These are not random,
they have been pre-calculated for both length and placement depending upon the desired result)
A lawn sprinkler is put in the center. This would be the kind of sprinkler that rotates a single spray of water in a constant circle. (It will probably be necessary to modify the sprinkler to adjust the spray of water to a really strong and consistent stream.)
As the sprinkler head rotates, water strikes each tube in turn. Each of these tubes has been tuned to a particular musical note and the placement of the tubes controls the rhythm of the melody.
The result is a large music box style piece of art that plays a repeating melody as the sprinkler rotates.