Some bronze mirrors give a curious effect. When a light is shone on the apparently smooth mirror surface, an image of the design on the back is seen reflected on a wall or screen. Some Japanese mirrors show this effect - perhaps one in a hundred. The mirror in this video (dating from the late 19th / early 20th century) is one of these. Here we repeat an old experiment - heat the moulded back of the 'magic' mirror, and the reflected image becomes bigger and sharper. The increased sharpness helps us to understand how the image is formed. (More details in a forthcoming publication.)