28,370. Moorhouse, A. H. Dec. 9. Theatrical appliances.-Relates to the apparatus described in Specification 24,815/10 for producing sound effects, and consists of a device for imitating the sound of waves dashing on the shore. A mat or apron b of woven - wire cloth or other metallic fabric is attached to an arm c secured to a rotatable shaft e. A drumskin a which is slightly inclined to the horizontal surrounds the shaft e, and a number of metal balls d rest on the drum-skin. The apron as it moves over the skin produces the sound of the waves, and when it is brought to rest, the balls d roll to the edge of the drum and produce the sound of water receding over shingle.