The evidence for this comes to us from the phenomena of light. Experimentally, ether waves of all lengths are found to have a velocity of 186,000 miles in a second. It takes about eight minutes to reach us from the sun, four hours from Neptune the most distant planet, and from the nearest fixed star about three and a half years. Astronomers tell us that some visible stars are so distant that their light requires not less than ten thousand years and probably more to reach us, though travelling at the enormous rate of 186,000 miles a second. This means that the whole of space is filled with this medium. If there were any vacant spaces, the light would fail to get through them, and stars beyond them would become invisible. There are no such vacant spaces, for any part of the heavens shows stars beaming continuously, and every increase in telescopic power shows stars still further removed than any seen before. The whole of this intervening space must therefore be filled with the ether. Some of the waves that reach us are not more than the hundred-thousandth of an inch long, so there can be no crack or break or absence of ether from so small a section as the hundred-thousandth of an inch in all this great expanse. More than this. No one can think that the remotest visible stars are upon the boundary of space, that if one could get to the most distant star he would have on one side the whole of space while the opposite side would be devoid of it. Space we know is of three dimensions, and a straight line may be prolonged in any direction to an infinite distance, and a ray of light may travel on for an infinite time and come to no end provided space be filled with ether. How long the sun and stars have been shining no one knows, but it is highly probable that the sun has existed for not less than 1000 million years, and has during that time been pouring its rays as radiant energy into space. If then in half that time, or 500 millions of years, the light had somewhere reached a boundary to the ether, it could not have gone beyond but would have been reflected back into the ether-filled space, and such part of the sky would be lit up by this reflected light. There is no indication that anything like reflection comes to us from the sky. This is equivalent to saying that the ether fills space in every direction away from us to an unlimited distance, and so far is itself unlimited. 3. MATTER IS HETEROGENEOUS.