582 HENRY A. ROWLAND 



and diffraction bands, that would prove instantly that the Rontgen rays 

 are waves. But I have never seen the slightest phenomenon of that 

 sort. It is very doubtful that it exists, and those persons who have had 

 it will have to show their photographs very clearly to make us believe 

 it. And therefore we have no evidence whatever that the rays are 

 waves. At the same time we have no evidence that they are not waves. 

 They might be very short waves infinitely short waves. Let us see 

 what would happen if they were infinitely short waves. They might 

 be so very short as to be too fine-grained for any of our methods of 

 polarization or reflection. Waves are reflected from a solid body 

 regularly reflected, because they interfere after they come from the 

 body. You can get the direction the angle of incidence equals the 

 angle of reflection; you can get that by means of considering them as 

 waves and as interfering after they come from the object. Well, if the 

 object, however, is a very rough sort of thing compared with the wave- 

 length, you will not get a regular reflection. That is what might hap- 

 pen in the case of Rontgen rays. And then again, with regard to 

 refraction of the light, the theory of refraction which comes from con- 

 sidering molecules imbedded in the ether will give you some limit. 

 When we go beyond that limit, we get no refraction. The bending of 

 the violet rays increases up to a certain point and then goes back. We 

 have a case of anomalous refraction very often in some substances like 

 fuchsine, aniline dyes, and so on. Therefore the action of refraction 

 can be accounted for by having very short waves. But when we treat 

 of the theory of the case we have the little molecules of a gas knocking 

 against each other, and they can only go a little distance. We call that 

 the free path of the gas a very small distance in the ordinary air. 

 Those molecules cannot go more than this very small distance before 

 they stop. Well, now, why should little, short waves of light pass 

 through the gas and not be stopped too? When the waves are very 

 short indeed, it seems to me that the object would be entirely opaque 

 to them, because they would strike upon those molecules, unless they 

 could pass directly through the molecules. You would therefore neces- 

 sarily have these little short waves going directly through the mole- 

 cules, which we generally think is almost impossible in case of light. 

 And that is one very great objection that I have to that theory. 



Then we have another theory that these are not transverse waves 

 at all; that they are waves like sound, and very short indeed. Well, 

 what would happen then? If they are very short indeed, you have the 

 same objection: They would all strike against the molecules, and they 



