PROCEEDINGS OF THE OHIO ACADEMY OF SCIENCE. 333 



In 1904 Morley and Miller repeated the experiment of 1887, 

 using a very much larger apparatus, the path of each of the 

 interfering beams of light being now 32 metres, instead of about 

 II, as in the previous experiment. The mirrors were separated 

 by rods of pine, instead of sandstone, and the experiment was 

 carried out as before. But the result was the same. No effect 

 could be discovered which seemed to show that the earth drifts 

 or moves through the ether. The ether appears to be carried 

 along by the earth in its orl)it. or else all substances suffer equal 

 dimensional changes when in motion. The Fitzgerald-Lorentz 

 hypothesis apparently takes the question out of the region of 

 experiment. 



The mathematicians now took the matter up, and under the 

 leadership of Einstein and Minkowski put forward the principle 

 of relativity in all measurements of space and time, which not 

 only did away with all possibility of raising questions as to a 

 fixed or moving ether, but went far toward doing away with 

 the ether itself. That is, as Lorentz remarks, the chief value 

 of the ether in this discussion is to furnish us with a fixed sys- 

 tem of reference-coordinates. Since it does not seem to fulfill 

 this function, many of the relativists abandoned it, sweeping 

 away with the Michelson-Morley difficulty, the hypothetical sub- 

 stance which gave rise to it. And there the matter rests at 

 present. 



This solution, however, avoiding one difficulty, raises many 

 others. Some sort of corpuscular theory of light would seem 

 to be necessary. It is interesting to note in this connection, that 

 certain phenomena of radiation, and some in the domain of heat, 

 seem best explained at present by a sort of corpuscular theory 

 of energy, in which the emission of energy takes place not con- 

 tinuously, but in successive steps, or quanta, as Planck calls 

 them, as if energy, like matter, is molecular in its nature. But 

 what is light, if it is not an ether-wave, and what of such 

 l^henomena as polarization, interference, and dift'raction ? This 

 is perhaps the most notable problem of modern physics. Here 

 are two great series of facts, each leaning toward its own hypoth- 



