As has been said, light moves with the velocity of 186,000 miles per second, and it may pursue its course for tens of thousands of years. There is no evidence that it ever loses either its wave-length or energy. It is not transformed as friction would transform it, else there would be some distance at which light of given wave-length and amplitude would be quite extinguished. The light from distant stars would be different in character from that coming from nearer stars. Furthermore, as the whole solar system is drifting in space some 500,000,000 of miles in a year, new stars would be coming into view in that direction, and faint stars would be dropping out of sight in the opposite direction--a phenomenon which has not been observed. Altogether the testimony seems conclusive that the ether is a frictionless medium, and does not transform mechanical motion into heat. 8. MATTER IS ÆOLOTROPIC. That is, its properties are not alike in all directions. Chemical phenomena, crystallization, magnetic and electrical phenomena show each in their way that the properties of atoms are not alike on opposite faces. Atoms combine to form molecules, and molecules arrange themselves in certain definite geometric forms such as cubes, tetrahedra, hexagonal prisms and stellate forms, with properties emphasized on certain faces or ends. Thus quartz will twist a ray of light in one direction or the other, depending upon the arrangement which may be known by the external form of the crystal. Calc spar will break up a ray of light into two parts if the light be sent through it in certain directions, but not if in another. Tourmaline polarizes light sent through its sides and becomes positively electrified at one end while being heated. Some substances will conduct sound or light or heat or electricity better in one direction than in another. All matter is magnetic in some degree, and that implies polarity. If one will recall the structure of a vortex-ring, he will see how all the motion is inward on one side and outward on the other, which gives different properties to the two sides: a push away from it on one side and a pull toward it on the other. THE ETHER IS ISOTROPIC. That is, its properties are alike in every direction. There is no distinction due to position. A mass of matter will move as freely in one direction as in another; a ray of light of any wave-length will travel in it in one direction as freely as in any other; neither velocity nor direction are changed by the action of the ether alone. 9. MATTER IS CHEMICALLY SELECTIVE.