In a career waymarked by innovation and the unexpected, guitarist Pat Metheny, at age 55, has pulled another surprise out of the pack. This time it's his use of an orchestrion, a steam age contraption which plays a battery of real instruments—wind, percussion, fretboard and keyboard—blown or struck by mechanical devices. In the nineteenth century, orchestrions were usually activated by cylinders resembling oversized piano rolls. In 2010, the cylinder has been replaced by digital software. On Orchestrion, Metheny is the only "live" musician, soloing over the beast's pre-programmed arrangements. It's the very definition of retro-modern.

Metheny will be taking the orchestrion on the road—a European tour in February and March will be followed by a North American tour in April and May—and he recently gave journalists a sneak preview of the instrument in Manhattan's Legacy Studios. It is, by all accounts, impressive: a phalanx of pianos, "guitar bots" (regular guitars and bass guitars with clamp devices moving up and down their fretboards to create different notes), a marimba, a vibraphone, a deconstructed drum kit (every cymbal and drum with its own brush and stick), a wind section made up of bottles and gallon jugs which light up as air is blown across their mouthpieces, and other customized or newly invented instruments.

Onstage, Metheny and the orchestrion are going to be quite a trip. On Orchestrion they are too, though not, inevitably, to the extent anticipated for the gigs. It is, after all, pretty much irrelevant on an audio disc whether Metheny's accompaniment is played acoustically or electronically, by flesh and blood musicians, trained dolphins or computer-triggered mechanical devices—so long as it cooks.

Most of the time, Orchestrion cooks. The only less than wholly successful exception is the opening title track, into which Metheny has thrown every instrument in the orchestrion, as though to illustrate its size and detail. Visually, "Orchestrion," which will presumably open the stage shows, will be a fascination; in purely audio terms it's over-egged and lacking in dynamic variety. The rest of the album is stronger, the arrangements less rich and Metheny's improvisations, rather than their accompaniments, at the center of things. In the promotional material accompanying review copies, Metheny says that the project has "gotten some notes out of me that I didn't know were there." In a purely literal sense, there is indeed a degree of astringency in some of his solos, particularly noticeable in "Expansion," which is unusual.

Elsewhere, on the bluesy "Soul Search," in which the shade of