Abstract: A clock comprising, a case, a clockwork in the case having a plurality of pointers, a dial face in the case over which the pointers sweep about a common axis, a glass covering the dial and pointers, at least one illuminator for illuminating the dial and pointers and a ring having a face with spaced markings thereon which is mounted between the dial and glass and which can be manually rotated. The ring face is illuminated by the same illuminator which sheds light on the dial since the ring face faces the glass which receives light from the illuminator and illuminates both the dial and the ring face.

Abstract: The clock comprises an electronic part including a quartz oscillator controlling a motor. The motor drives, through a wheelwork, both continually running hands and stoppable hands. By means of a manually operated actuator, the stoppable hands can be operatively connected to, or disconnected from, the motor, or reset to zero. With the motor running, the continually running hands can be set to a desired time by means of a hand setting actuator. The crystal-controlled drive provides for high accuracy and the analog indication of the time and of the clocked intervals make reading convenient and fast.

Abstract: A welder's helmet has a window with an upper section of invariable light-attenuation characteristics and a dimmable lower section comprising an ultraviolet filter, an infrared filter, and an electro-optical shutter such as a liquid crystal sandwiched between a polarizer and an analyzer. A control circuit including a UV-sensitive photocell, upon sensing a welding arc or flame, operates the shutter to reduce the amount of light transmitted through the lower section of the window.

Abstract: A welder's mask has a lens at least part of which is formed of an infrared filter, an ultaviolet filter, a polarizer, an analyzer, and an optoelectric element between the polarizer and analyzer. The optoelectric element may be a ceramic crystal or fluid crystal that is electrically energizable by means of automatic circuitry connected to an UV-sensitive photocell to rotate the polarization plane of light coming from the polarizer to the analyzer in order automatically to darken the lens when exposed to a welding flame or arc.

Abstract: The variometer includes a measuring chamber communicating with the atmosphere through a first passageway and an elastically deformable measuring box, positioned within the measuring chamber, communicating with the atmosphere through a second passageway. One of the passageways, preferably the second passageway, is provided with a system of orifice inserts serving to delay pressure equalization between the measuring chamber and the measuring box. The system of orifice inserts includes at least two orifice inserts with successive orifice inserts being separated from each other by an intermediate space. The orifice inserts are threaded into the internally threaded bore of a hollow screw, and preferably three orifice inserts are provided so as to define two intermediate spaces. At least one of the orifice inserts is displaceable axially of the hollow screw, and preferably two orifice inserts are so displaceable.