76 THE ANATOMY OF SCIENCE 



certed to find that the shells are arriving ahead 

 of the water wave. The captain explains that 

 this is due to the fact that the tide has changed 

 and that the water waves, which before were 

 running with the tide, are now running against 

 it. 



Now in the early discussion of light its prop- 

 agation seemed more to resemble the propaga- 

 tion of waves upon water than the course of a 

 projectile through the air, and therefore it was 

 assumed that light must have a carrier, and this 

 carrier was called the ether. If a searchlight 

 were playing upon some object, the way in 

 which light travels would thus be supposed to 

 depend, not only upon the searchlight and per- 

 haps upon the object and the kind of light, but 

 also upon the properties and motion of the ether 

 which carried the light. This assumption has 

 proved to be entirely gratuitous, serving to 

 complicate a simple problem. Yet this belief in 

 the ether, together with the belief in the validity 

 of the Newtonian kinematics, held despite the 

 numerous presages of paradox, which became 

 the more alarming as experimental physics 

 began to deal \\dth velocities, not of a few feet 

 or a few miles per second, but with objects like 



