The design and modeling of a novel technique for particle-size distribution analysis are described In its most basic form, the unit comprises a horizontally held closed-coil helical spring that is partly filled with the test powder find sinusoidally vibrated ill the transverse direction. Particle-size distribution data are obtained by tretching the spring to known lengths and measuring the mass of the powder discharged fi om the spring resonant frequency. The spring's vibration characteristics, including the dynamic vibration profile as well as its first harmonic resonant frequency, are predicted using a viscoelastic model, which is in turn validated by comparison with experimental data. Particle-size distribution data are reported in conjunction with a variety of powders including glass Ballotini, grit stone, sand, and sawdust in the size range 30-800 mum. A typical reproducibility is +/- 4%.