Bart Hopkins is mad, but his is an elegant madness.Some people collect sounds -- it is a mania common to musicians, for whom sometimes the whole clattering world seems to be made of potential instruments. They bend saws and take cello bows to them, creating near-human moans. They string and amplify tennis rackets like guitars. They record industrial saws and drill presses and arrange the recordings into a symphony of mechanical voices. They build libraries of sounds and hear each as voices, singing in their own peculiar way. And Bart Hopkins, in his own madness, collects the collectors.Hopkins has compiled and released, through Ellipses Arts, a two-CD collection of music by found and invented instruments. Titled after the idiosyncratic names applied to these instruments (Gravicords, Whirlies & Pyrophones and Orbitones, Spoon Harps & Bellowphones), the CDs contain 35 tracks as peculiar as the instruments that created them. The sound is sometimes, as Tom Waits says in his introduction, "more insect ritual than human."It is also sometimes starkly beautiful, as is the case of Jaques Dudon's aquavina. Dudon has an obsession with creating music using water, and this invention is essentially a lute with a water bowl for a body. As Dudon plays, running a bow across the instrument's strings, the motion of the water in the bowl causes the notes of the song to curve and glide. Dudon's composition "Naades," included in the Gravicords CD, has a shimmering, ethereal quality as a result. It sounds as though a hole has been punched in time and a glorious Persian prayer from the time of The Arabian Nights had struggled through, twisting itself in the process until it was unrecognizable.Elsewhere, Sharon Rawcliffe's clay flutes produce sounds that hardly resemble music. Her heavy, sweet potato-shaped noisemakers thunder and cry like a soundtrack to a prehistoric rainforest. "They are only for the stronghearted," she admits in the voluminous liner notes that accompany the two CDs. This time it is we, the listeners, who have been thrust through time, into the past. As Rawcliffe's flutes roar and whistle, it is as though we were witnessing the dawn of music itself. In fact, many of the recordings Hopkin has compiled seem to be a document of the evolution of musical instruments, including cavemen thumping on rocks."People are tinkerers," Hopkin explained from his office in Nicasio, Cal. Hopkin began and has been the sole driving force behind Experimental Musical Instruments, an organization and semi-regular publication exploring the fringes of melodymaking. While the magazine will cease printing with its next issue, Hopkin stressed that the organization will continue as a "general resource center for instrument making." Among these resources will be self-published books on instrument making, a few authored by Hopkin.Self-made and experimental instruments are not an easy passion. Even those made of ordinary household objects, such as Barry Hall's flowerpotophone, require considerable thought. There is the construction, which required (in Halls' words) "lurking in the flowerpot section with a rubber mallet and a pitch pipe." Then there is the mastery of an instrument that, as Hopkin relates in his intro to the CD collection, no one has developed the skill to play," neither has it "a familiar repertoire to give it a popular identity. It will not be imbued with the cultural richness of older instruments, and no one will know what its expressive capabilities are."But this is the challenge for the musical adventurer. If no one has ever played a stiltophone (a bellows-like instrument built out of stilts), then the inventor-musician-composer will be the first to discover the sounds that it makes. In the words of Hopkin, a new instrument "will take you musical places that you would never have thought of sitting at a piano."With many of the instruments in Hopkin's compilation, the results sound like folk melodies -- perhaps African, perhaps Asian, perhaps Middle-Eastern. But with tracks like those produced by Qubais Reed Ghazala's "circuit-bent" instruments, they sound like no noises on earth. Ghazala tinkers with existing electronic devices, such as the Speak and Spell child's toy, but modifies them so that they produce new noises -- often on their own. His Video Octavox, for example, drapes over a television set like an exhausted squid and uses light sensors on its many tentacles to read the images on the TV screen and convert them into sound. The resulting squeaks and chirps bear no relation to the tones, scales and rhythm of any human music. They chatter their own incomprehensible tunes, oblivious to us, singing without knowing that they do so.Hopkin has pursued and captured this astonishing variety of instruments and instrument makers for so long that, like a butterfly enthusiast with a net and a pinboard, he has virtually broken them down into genus and given them Latin names. He discusses with enthusiasm the way new instruments forge new physical relationships with their makers. While a guitar-shaped instrument will always retain a guitar-like quality as its player strums and plucks it, there has never been an instrument that could be played like the theremin.Named after its inventor, Leon Theremin, it was the first truly electrical music maker. The instrument consists of a box with two antennas, and the musician plays by waving his or her hands in the air near the antennas. The hands interrupt electrical signals from the machine's two high-frequency oscillators. The science is tricky (Theremin would eventually be kidnapped from the United States back to his native Russia, where he was put to work building eavesdropping bugs), but the music is not. The theremin produces an exquisite high tone, today mostly associated with the soundtracks to science fiction movies, but when played by a virtuoso such as Clara Rockmore (such as her performance of "The Swan" in this collection) the sound is chilling. It is a measured, shifting wail, as though a cry of despair had been converted into melody.The early theremins were beautifully handcrafted, looking like a mix between an art deco wooden cabinet and an antique radio set. Indeed, many of the instruments in Hopkin's collection are physically beautiful -- without knowing their function they might be mistaken for sculptures or objets d'art. In part, this is of necessity, as Hopkin pointed out that "the demands of making something that works acoustically often leads to interesting visual forms," but in part it is also because many of the instrument-makers Hopkin profiles are as engrossed by the process of making the instruments as they are by the eventual sounds they produce. They use a dazzling range of materials, from sheets of metal to eagle feathers, and do not seem to mind if the thing they create can never be recreated. Hopkin calls these "one-of-a-kinds," and it is startling to look as some of these vast loom shapes (such as the simply named long string instrument) or hanging globes of glass (such as the cloud chamber bowls of experimental musical instrument pioneer Harry Parch) and realize that they produce sounds.It defies our understanding of music that something like Ela Lamblin's stamephone -- a great, gorgeous stringed metal globe -- exists only for the sake of one player. In fact, it defies the essentially democratic nature of music. Any one can purchase a harmonica for a few dollars and, blowing for long enough, will produce some kind of noise. But the stamephone can have only one owner and one master.But if it runs contrary to musical democracy in this way, it supports it in another. Because Hopkin's mad mission with his Experimental Musical Instrument organization is not to expose us to other artists' assemblages of noise, it is to encourage us to make our own noises. "We're really there for people who are into making instruments more than, say, making instruments that other people would want to buy -- or making music with instruments that people would want to buy the CD," he explained.His CDs, therefor, exist as less a report of new lands than as a road map to them. We are not expected to remain at home, thrilling to the sounds of the zgamoniums and pencilinas as Europeans must have at one time thrilled to the exploits of Marco Polo. Instead, we are expected to pack our bags and head East, forging our own adventure. Hopkin's madness is there for us to take as our own, if we want it.