Nuclear bomb attack

When I worked briefly on Capitol Hill in Washington DC, I was in the Canon House Office building.  At the ends of the corridors were yellow and black propeller signs telling people what to do in the event of nuclear bomb attack.  If the bell sounded three long bursts in succession, people were to make their way immediately to the designated shelters in the basements.

One quiet day I was alone in the office, with everyone else off to meetings.  At 11 am the bell rang a long burst.  Then it sounded again, another long one, and I wondered idly if it would sound a third time.  It did.

There was no rush of footsteps in the corridor.  Indeed, as I looked out there was no-one there at all.  I walked rather nervously along the empty corridor past what seemed to be empty offices.  My alarm was rising by the time I reached an intersection; where to my relief I encountered a solitary policeman.  I approached him.

“Did that bell just sound three times?” I asked.

“Sure did,” he confirmed.

“What does that indicate,” I enquired.

“Nuclear bomb attack,” he informed me in a bored, offhand manner. 

Then, seeing my expression, he added helpfully, “It’s tested every Wednesday at 11 am.”

I was much relieved, and told him that if I were the Russians, that’s when I’d attack.