
A man is strolling past the mental hospital and suddenly remembers an important meeting.
Unfortunately, his watch has stopped, and he cannot tell if he is late or not. Then, he notices Arivukanru similarly strolling about within the hospital fence.
Calling out to Arivukanru, the man says, "Pardon me, sir, but do you know the time?"
Arivukanru says, "One moment!" and throws himself upon the ground, pulling out a short stick as he does. He pushes the stick into the ground, and, pulling out a carpenter's level, assures himself that the stick is vertical.
With a compass, he locates north and with a steel ruler, measures the precise length of the shadow cast by the stick.
Withdrawing a slide rule from his pocket,Arivukanru calculates rapidly, then swiftly packs up all his tools and turns back to the pedestrian, saying, "It is now precisely 3:29 pm, provided today is August 16th, which I believe it is."
The man can't help but be impressed by this demonstration, and sets his watch accordingly.
Before he leaves, he says to Arivukanru, "That was really quite remarkable, but tell me, what do you do on a cloudy day, or at night, when the stick casts no shadow?" Our Arivukanru holds up his wrist and says, "I suppose I'd just look at my watch."