 During this interruption, another contactor closed and a sentry (searchlight) was exposed across the river, on a bearing a few degrees inside the line of the infrared PE beam.The service contactor switch for the searchlight was then closed by the switchman, who carried out a quick search of the area; the control panel contactor being immediately reset by pressing a button on the control panel.Resetting stopped the alarm buzzer, flashing light and the clicking in the loudspeaker, leaving the apparatus ready to give another signature immediately.