Abstract: An apparatus for the injection of liquid additives, such as fertilizers and insecticides, into irrigation sprinkler systems for even dispersal within the least distance of conduit pipe from the point of injection is presented. Said injection is accomplished by injection of the additive through a hollow L-shaped spindle about the horizontal arm of which is a rotatable hollow hub from which extend hollow injection tubes, along the length of each there being a semi-circular impeller blade. The apparatus, centrally located within the conduit pipe of an irrigation system, disperses pressure-injected additive while the rush of water through the conduit causes the impeller to rotate, thus further facilitating dispersion of the additive.

Abstract: A saw wherein an arbor is mounted to drive a circular saw blade from below a flat work surface upward through a slot in the work surface to sever any work piece suitably disposed on the work surface. A guard/clamp above the work surface is lowered to engage and clamp each such work piece on the work surface before the saw blade begins its ascent. A sensor is mounted on the guard/clamp to sense the presence of a work piece at a location immediately on the work piece feed side of the saw blade and adjacent a saw fence. The sensor prevents operation of the saw when the sensor fails to establish the presence of a work piece on the work surface.