Abstract: The assembly has two lamps, such as fluorescent tubes. A cover is a co-extrusion having a baffle between the lamps and shroud portions outermost of the cover. The baffle blocks at least some of the light output of the lamps from crossing the region between the lamps. This helps reduce glare, which is further reduced by the configuration of the shrouds.

Abstract: The assembly has two lamps (16A, 16B), such as fluorescent tubes. A cover (18) is a co-extrusion having a baffle (20) between the lamps (16) and shroud portions (22) outermost of the cover. The baffle blocks at least some of the light output of the lamps (16) from crossing the region (26) between the lamps (16). This helps reduce glare, which is further reduced by the configuration of the shrouds (22).

Abstract: A source of seismic waves operable within a borehole filled with liquid crises a module supported by a cable. The module includes means to generate a high voltage and to charge a bank of capacitors, and means to connect the capacitors across a pair of electrodes forming a spark gap. The electrodes are immersed in liquid at the same pressure as the borehole liquid and acoustically continuous with it, and are separated by a gap of width between 0.5 and 20 mm. If the gap is greater than about 5 mm, both the electrodes should be covered with insulation except at the positions where the spark is to be formed. The module can operate automatically at considerable depths and at high pressures.