Abstract: A sighting lens has a refraction displacement of the image such that upon selected positioning of the lens on a weapon, such as an archery bow, and using a reference point therewith, a novel sighting procedure for hunting animals can be used which comprises aiming a selected distance below the image of the animal as it appears in the lens. Prisms are included to correct the line of sight which may not be true because of offset mounting of the sighting device. Increments of distance are provided on the lens for assisting the archer in aiming at a distance which is beyond normal shooting limits of that particular sight.

Abstract: A dual path analyzer and a single path analyzer are disclosed, each for determining the concentration of one or more gaseous components in a mixture of gases. The preferred analyzer is a single path instrument which includes a source of infrared energy, a detector for the energy, a sample cell for the gas mixture positioned between the source and detector, and a filter wheel having a plurality of filters and a source blocking device positioned between the sample cell and detector for sequentially interposing the filters and the source blocking device between the source and the detector. Means are provided for amplifying the output signal of the detector and for processing the signal to provide a direct readout display which indicates the concentration of the gaseous components being analyzed.