The Miller's sons all have tremendous lung capacity, which first reveals itself in their crying. But the Miller trains them in this skill so the can become tremendous "blowers", trying to make them into musicians on the bugle, flute, trombone, etc. But they had no music in them, only loud noises. So he uses them to blow on his windmill on breezeless days, so he can still grind grain, and he becomes a wealthy grain merchant. Then, when the King's son is to cross the sea to marry a neighboring Princess, their ship is becalmed, and the Miller's sons are recruited to blow the ship in to port. As reward, the ten sons all receive great gifts, and all marry Princesses.
