A S yet, even the most expert ornithologists know little of the great mystery of bird migration-where the birds go that leave us when the autumn comes and the leaves begin to fall; but this at least we all know-that when the migrants return, the harsh days are over and summer is at the door. In this talk, Mr. Eric Parker will describe the double movement that goes on when those migrants that have sought shelter here move North again, and those that left us last year return from the warmer South.