Abstract: A ranging system for a camera is provided including a reflecting means and marking means including movable masking means reflected thereby into the viewfinder of a camera. The reflecting means within the scope of this invention includes means for translating an axial movement of the movable masking means to the camera viewfinder as a positional movement transverse to the actual displacement direction thereof. To effect this image transfer, the marking means includes at least one mirror mounted adjacent to the masking means at an angle of about 45 degrees to the displacement direction thereof. According to one embodiment of the invention, an annular mark is projected into the viewfinder. To project an image of this character, the marking means includes an interiorly mirrored conical member, and the masking means includes a mandrel axially mounted therein, the mandrel being displaceable along the conical axis.

Abstract: A mass producible therapeutic device for massaging gingival tissue is disclosed. In the body of the device, oppositely oriented arcuate channels are formed comprising respective recesses generally suited to the conformation of the teeth and adjacent structures. The channels are generally defined by respective pairs of substantially parallel thickened longitudinally extending sidewalls connected through a common interior lateral extension. The body of the device is interiorly slotted or channeled for carrying a fluid, such as air, and the material thereof is sufficiently impermanently deformable so that as a user reciprocably chews into the arcuate channels the effects of fluid redistribution within the body and the elastic character thereof cause the thickened longitudinal sidewalls of the device to flex inwardly against the crowns of the user's teeth for frictionally removing plaque therefrom.