I hesitate to post this, but I like to know how things work, so you'll have to forgive the toilet talk. It concerns gents urinals. There are usually two methods of flushing: the timed flush, common in England, where every n minutes the urinals are flushed, and the sensor based which detects when the urinal has been used. This sensor is usually a light based one; the approaching gent blocks light to the sensor and when done the return of light activates the flush. Last week at the conference centre there were no visible sensors but when done the flush happened. Both Alex & I noticed this independently (for the ladies out there, gentleman don't have to go to the toilet in pairs) and both tried to figure out how it works. Every trip to the loo was like a little scientific exploration, full of potential. The only solution we could come up with was water depth based, but that requires quite accurate sensors. I'm sure I could ook it up somewhere, but that's far too easy a solution.