of Light and its Theory. 257 



that polish consists of inequalities which, in reference to their 

 distances from each other, are smaller than w, they will be no 

 disadvantage either to the light passing through, or to that 

 which is reflected, nor can colours of any sort arise from 

 them. It would likewise be impossible, by any means, to ren- 

 der these inequalities visible.* If small inequalities had acted 

 upon the light, for instance, according to the law of reflection, 

 the rays would become in the highest degree irregularly dis- 

 persed, because the curved diameters of these small inequalities 

 cannot be otherwise than very small, and the regular reflec- 

 tion would be impossible. If a reflecting surface consists of 

 inequalities, the distances from each other being less than u, 

 then, as I have already said, no spectrum is posssible, and 

 only the light in the axis can return, fur this ray v=0, in which 

 case the equation (V.) at the same time also represents the law 

 of reflection^ namely cos. r (^) =z sin <?. This law also follows 

 from the interference, and it is unnecessary to assume a re- 

 flecting power, that' is vertical to the reflecting surface.-|- 

 That more light is reflected with a larger angle of incidence 

 than with a smaller, follows as plainly, and corresponds with 

 experience. It is remarkable, that, according to the uncor- 

 rected equation (III.) at distances, from the reflecting surface 

 which in comparison with w are not great ; that is, at very 

 small distances the angle of reflection may differ perceptibly 

 from the angle of incidence. From a proper examination of 

 this equation, it will be easily seen that at those distances 

 where one still can observe accurately the differences so small 

 that no one will think of finding it by an experiment, and 

 that thence the usual experiments for determining the law of 

 reflection will prove nothing against its derivation from the 

 theory ©f interference. 



From all the experiments with the different systems of lines, 

 it is clear that the distances of the spectra from the axis are 

 larger in proportion to the smallness of the distance between 



* From this we may conclude what it is possible to see through mi- 

 croscopes. A microscopic object, for instance, the diameter of which = », 

 and consists of two parts, cannot be recognized as consisting of more than 

 two parts. This shows us the limits which are set to vision through mi- 

 croscopes. 



t See Note A in page 260. 



