A gun carousel 100 including a main post 102 secured to a base 104, a center wing 106 secured to the middle portion of main post 102, and a top cabinet 108 secured to the upper end of main post 102. This device includes circuits for producing monopolar or bipolar stimulation pulses, selectively with or without disconnection of a connection to a reference potential, and a circuit for sensing a pulse signal produced by the variation of potential induced on one andor the other of terminals andor on the metallic case in response to an application of stimulation pulses. A prism is disposed over the opening and is operable to direct at least a first portion of the light beam toward the opening to the liquid such that the at least a portion of the first portion of the light beam is reflected back from the liquid forming an attenuated beam. The type of coating is determined from the magnitudes of reflections from the surface coating of one or more different wavelength light beams. The method also includes controlling a bandwidth allocation associated with the end user based on one or more of the RSVP actions. In outputting its result as a final biological signal, the biological signal value at each of points in time included in the missing section is changed to an average value of the biological signal values at points in time which are not in the missing section.