Pollio, Vitruvius, and Daniele Matteo Alvise Barbaro. 1567. I Dieci Libri Dell'architettura Di .. Vitruvio / Tradotti & Commentati Da Daniel Barbaro. Giovanni Chrieger. doi:http://doi.org/10.3931/e-rara-26800 .
Wooden sticks, when dropped on the floor, sound a variety of tones. While the bars of a xylophone are varied in tone by changing their length, these “tone bars” are all of the same length and width, but have different thicknesses and different densities and elastic properties.
