Erewhon I an image of a world in genesis, of a pure space in action. Jolts, spirals, turbulences, jerks. Shapes become entangled, embedded, or mutually crushed by the pressure of the dynamism that agitates them. The violence of the form strives for the densest possible concentration, for the tightest interweave. It breaks and contracts - a formalism of collision and fracture. Membranophonous percussion is particularly adapted to brutal metamorphoses - freed from pitch constraints, it relates only to the energetic aspect of sound. With a sufficient number of instruments, an actual keyboard of dynamic impulsions is put at our disposal: sharp dry attacks, muted collisions, shocks with colourful resonance, or dull impacts. The rhythm, meter and dynamics are totally dissociated. It is their interweaving that creates the work's tension. The implementation consists of articulating the explosive configurations between themselves, playing more or less on their structural conflicts. Erewhon II is a fantastic trial of stereo-dynamics. What would happen to a space that was suddenly saturated with every possible form of energy, as released from the mesh of the universe? Perhaps a world of pure movement without discernable limits would emerge, an upheaval of quavering architectures, the sudden proliferation of a blaze of interferences.To translate the image of that effervescent complexity, I attempted to construct a changing architecture of metallic timbres (steel plates, cymbals, gongs, tam-tams) where fluidity, ambiguity and indeterminate transitions would prevail.An interplay of incessant shifts, with the sonic masses' mutual superimposition tending to produce an effect of undetermined flight. The superposition or fluctuation of timbres, alternately emptying and enlarging the sound wave, makes up a rhythmical element.Another form of scansion: blocks of light implanted within the mass (vibraphones, glockenspiels) rising upward in a radical looming movement. In this work, I attempted to systematically use the specific qualities of metal percussion instruments: modifying the timbre through the attack, slowly transforming the sound's colour by rolling with soft mallets (steel sheets, gongs, tam-tams), using particles of resonance (a cymbal's progressive sparkling), and modulating the resonance's dynamic spectres. Metal percussion instruments profoundly modify the relationships between sound production and perception. It brings the traditional balance (instrumental or vocal) between articulating movements and the acoustic waves they create into question. This dynamic coefficient typical to metallic resonance must be taken into account, giving rise to a new class of 'fluid' sounds. Erewhon III an adagio for percussion that treats the instruments like voices: gongs, bells, tubular bells, cowbells, tympani, marimba. In this work, I intentionally took the percussion's overall sound dynamic into account. Striking a gong or scraping a tam-tam means creating a forceful event with a centre (the impact), and a zone of radiation (the radiating signal). Metrical time is completely subordinated to the internal length of the phases of resonance. In addition, the resonance of a metallic instrument produces a form with a shape dictated by a movement of internal expansion. It provides the sound space with a law for development, for curvature, marking it with an evolving speed. The physical properties of the resonance produced by metal instruments outline, in themselves, an expressive geometry. I have attempted to take the best from this alphabet of configurations, fleeting, but clearly differentiated by their spectres of dispersion. Using them requires an organisation specified by laws of affinity or contrast. Lastly, the treatment of the bells and gongs presents a particular harmonic problem: we are confronted by hybrid sounds that are sometimes heard as defined pitches, other times as complex sounds (bundles of harmonic spectres), clear in tessitura, but w