As the editor of the self-explanatorily journal Experimental Musical Instruments, Bart Hopkin knows a thing or two about unusual methods of creating music. With Orbitones, Spoon Harps & Bellowphones, a sequel to the similar Gravikords, Whilies & Pyrophones, Hopkin has assembled the work of 14 artists who use instruments of their own invention. While the familiar Tom Waits, Stomp, John Cage, and Aphex Twin are all here, Hopkin has also included some truly peculiar methods of making music. The Belgian group Les Phônes, for instance, has concentrated most of its energy into the stiltophone, a flute-like instrument encased in stilts that is played when the members of the group dance about on them. Ela Lamblin adopts a similarly interactive approach to his creations, which include the orbitone of the book's title, a giant swing which creates sounds when ridden. But the accompanying CD proves that Hopkin has chosen his subjects for reasons other than novelty value: Even without the benefit of visuals, both the stiltophone and the orbitone sound quite beautiful, as do Colin Offord's Great Island Mouthbow and the American Gamelan invented by Bill Colvig and Lou Harrison. As both a book and a CD, Orbitones does little more than scratch the surface, but as an introduction to some unique musical instruments and the creators behind them, it's excellent.