Abstract: An electric lamp (1) comprising a gastight lamp vessel (2) for the transformation of electrical energy into light, which lamp vessel has two current conductors (3,6; 4,7) which extend to the outside. The lamp further comprises an outer envelope (9) in which the lamp vessel (2) is arranged with a space between the lamp vessel and the outer envelope. The outer envelope (9) has a lamp cap (11) to which the current conductors (6,7) are electrically connected. The lamp (1) further has means (17) for switching off the lamp by short-circuiting the current conductors (6,7) in the case of fracture of the outer envelope (9).

Abstract: A stationary guide plate (11) is formed with two locally intersecting profiled grooves (12, 13), which are profiled in conformity with a kinked path having a first and a second path section which are inclined relative to each other and of which a first groove (12) has a smaller width and a greater depth than a second groove (13). The profiled grooves (12, 13) are engaged by guide members (14, 15) which are connected to the object carrier (22) so as to be movable in the profiled grooves, and which have a transverse dimension corresponding at least substantially to the width of the respective profiled grooves.

Abstract: A mechanism is provided for varying the distance between a detector and a measuring crystal in an X-ray spectrometer. The crystal is arranged on a rotatable shaft and the detector is arranged on an arm which can perform a circular movement about the crystal shaft. The crystal shaft and the detector arm are coupled so that a rotation of the crystal shaft through an angle .theta. is accompanied by a rotation of the detector arm through an angle 2.theta.. A first pulley having a radius r is mounted on the crystal shaft and a second disc having a radius 2r is rotatably mounted on the crystal shaft. A belt or cord is guided over each one of two guide rollers. One end of each of these belts is permanently connected to the first pulley, while its other end is permanently connected to the second pulley.