1885.] The Relations of Mind and Matter. 1153 
enormously greater than that of the earth’s atmosphere can be if 
the atmosphere extends indefinitely into space, as is highly prob- 
able. The rigidity of ether is insignificant as compared with 
ordinary solids, yet its transmitting power is enormously greater 
than that of steel or glass, on account of its very slight density. The 
ether within glass transmits vibrations 40,000 times as rapidly as 
the particles of glass itself could do. But the atmospheric ether 
carries these vibrations at a speed one-half greater. The speed, 
therefore, is checked within glass to two-thirds its normal 
amount. Why isthis? Is ether affected by gross matter, and 
concentrated by attraction so as to increase its density? Fres- 
nel’s hypothesis is, that the ether is really denser inside gross 
matter. He thinks that_an attraction exists between ether and 
the molecules of matter which results in an agglomeration or — 
binding of some ether round each atom, and that this bound 
ether belongs to the matter and travels with it. The free ether 
may flow without check through the pores of matter, and even 
through those of the earth as it dashes onward through space, 
Refraction of light from sucha cause is attributed to bound ether, 
which seems to act differently on the different colors. 
Certain experiments have been tried to prove whether any of 
the ether can be bound. If ether is carried along with a moving 
stream, as of water, it should hasten the speed of light passing 
through that stream, If not carried by the stream there could 
be no effect on the speed of light. The results of these experi- 
ments have been favorable to the hypothesis. Yet the variation 
in the speed of light from such a cause is so slight that it is 
difficult to reach any very positive conclusions on this subject. 
That ether possesses energy is unquestionable. It moves with 
such extreme readiness that it cannot fail to possess a large sum 
of normal motions. Its physical condition also is indicative of 
conditions of energy. Elasticity, rigidity, solidity are due in 
matter to the interactions of attraction and motion, and we have 
no warrant to ascribe them to any other cause in ether. But the 
motions normal to ether are certainly very different from those 
normal to matter, since ether refuses to accept the motions com- 
municated to it by matter. This is what we must understand 
from radiant light and heat. Matter forces its motions upon 
ether, but the latter substance refuses to absorb them, and merely 
transfers them, with the utmost rapidity, to some distant mass of 
r 
