As knowledge increases, the attitude of science towards the things of the invisible world is undergoing considerable modification. Its attention is no longer directed solely to the earth with all its variety of objects, or to the physical worlds around it; but it finds itself compelled to glance further afield, and to construct hypotheses as to the nature of the matter and force which lie in the regions beyond the ken of its instruments. Ether is now comfortably settled in the scientific kingdom, becoming almost more than a hypothesis. Mesmerism, under its new name of hypnotism, is no longer an outcast. Reichenbach's experiments are still looked at askance, but are not wholly condemned. Röntgen's rays have rearranged some of the older ideas of matter, while radium has revolutionised them, and is leading science beyond the borderland of ether into the astral world.