‹‹‹ Vitr. 9.8.2 | Table of Contents | Vitr. 9.8.4 ›››
3Fixing a wooden tube under the beam, he attached pulleys to it upon which the cord passed and made an angle in descending into the wood which he had hollowed out: there he placed small tubes, within which a leaden ball attached to the cord was made to descend. It happened that the weight, in passing through the narrow parts of the tube, pressed on the inclosed air, and violently driving out at its mouth the quantity of air compressed in the tubes, produced by obstruction and contact a distinct sound.
3Under the roof-beam he fixed a wooden channel in which he arranged a block of pulleys. He carried the cord along the channel to the corner, where he set up some small piping. Into this a leaden ball, attached to the cord, was made to descend. As the weight fell into the narrow limits of the pipe, it naturally compressed the enclosed air, and, as its fall was rapid, it forced the mass of compressed air through the outlet into the open air, thus producing a distinct sound by the concussion.