Abstract: An electric vest for therapeutic heating of the upper torso. An insulated electrical conductor is fixed to a canvas matrix by means of metal clips. The canvas matrix in layout resembles a face shaped region with radially-directed ears shaped regions so that, when worn over the shoulders of user, the pectoralis muscles of the upper chest, the trapezius muscles of the upper back and the posterior cervical muscles are covered. The electrical conductor is fixed to a path traversing the canvas matrix whereby heating is simultaneously provided to the neck, upper back and upper chest regions of the wearer.

Abstract: A rapper for striking a target in a precipitator includes a hammer having a hub pivotally attached to a frame. The rapper also has a drive sprocket rotatably mounted in the frame. The sprocket has a driving plurality of spaced teeth distributed on the sprocket along a given peripheral sector. The latter cover less than the entire periphery of the sprocket. The teeth of the sprocket are distributed to mesh with and then release spokes on the hub of the hammer.