Abstract: A deflecting mirror is in the optical path between a monocular microscope for viewing the region of a layer on which an X-ray beam falls, and the region of a layer, the thickness of which is measured according to the X-ray fluroescence principle. The mirror is in an apparatus that has an X-ray beam generator which emits an X-ray beam along a longitudinal geometrical axis, a table device arranged to support the layer, a diaphragm device of a material which absorbs X-rays, having an aperture which is in the longitudinal geometrical axis, and a light source which can be directed onto the region for the layer. The mirror is composed of glass and has a hole at 45.degree. to the plane of the mirror. The longitudinal geometrical axis of the X-ray beam passes through the hole.

Abstract: A nickel bath for electroplating aluminum and aluminum alloys with nickel is comprised of high proportions of nickel sulfate, small proportions of an acid which stabilizes the pH values, and very small proportions of a fluoride which loosens the oxide layer appearing in the Licer bath, of a chloride which promotes the dissolution of the nickel anodes and of a phosphite which improves the adhesive strength of the nickel layer.The solids are kept in suspension in the bath by vigorous circulation, for example by means of air. The particle size should preferably be 3 micrometers.

Abstract: The apparatus measures the thickness of thin layers according to the X-ray fluorescence principle. It has an X-ray beam generator which emits an X-ray beam along a longitudinal geometrical axis, a table device arranged to support a layer which is to be measured, a diaphragm device of a material which absorbs X-rays completely, having a through-aperture which is moveable into the longitudinal geometrical axis, a light source for visible light which can be directed onto the region for the layer, a monocular microscope arrangement for viewing the region of the layer on which the X-ray beam falls, and a deflecting mirror in the optical path between the monocular microscope arrangement and the region of the layer. The diaphragm device is composed of a glass which is transparent to visible light, and has several through-bores therein of different cross-sectional geometry.

Abstract: A metallic crossbar device has mounting means for the end regions of spectacle frame yokes and space for a number of adjacent spectacle frames oriented in about the same direction. The cross-bar device comprises two crossbars which run parallel to each other and are spaced apart at a distance corresponding to the spacing of the end regions of the spectacle frame yokes. The crossbars have cross yokes at their end regions which rigidly connect the crossbars together. Each of the crossbars comprises two adjacent, flexurally stiff partial bars and clamping means for clamping one partial bar like a vice against an adjacent partial bar. The partial bars have a maximum clamping height which corresponds to the unprocessed length of the spectacle frame yoke end regions. Both partial bars have strip-shaped plastic clamping linings on their sides adjacent each other.

Abstract: A lens bow has a first area with a through hole oriented approximately in the direction of mechanical tension in the bow when it holds a lens set therein, and a second area with an inside threaded sleeve aligned with the through hole. The first and second areas have opposed faces. A screw has a head which rests outside the first area and which is tightened into the inside threaded sleeve to bring the first and second areas towards each other to hold the lens in the lens bow. The shortest distance between the opposed faces are larger in the untightened state and smaller when the screw is tightened to bring the bow into a holding condition about the circumference of a lens set therein.