Matsumoto Castle legend, the elongated beams

One legend of the Matsumoto castle says that during the construction works the builders discovered that one of the main beams was cut about 15 centimeters too short. Then, one of the carpenters came with a very odd proposal, telling the workers that he knows how to... elongate the beam.

He tied the beam with ropes on both sides and asked the workers, about one hundred men, to form two teams and to pull the ropes. He remained in the middle, and at one moment he hit the beam with a large mallet. After repeating the procedure a couple of times, they measured the beam again, and... it was exactly 15 centimeters longer than before!