Intelligence and Miscellaneous Articles. 



245 



(3.) Comhinatio7i of the observations and conclusions in III., 1. and 

 III.. 2. 



1 1 . The same direction of vi- 

 bration is connected with the 

 same tone of colour or the same 

 wave-lenffth. 



12. In the direction of the axis 

 we do not see the colour B because 

 the direction of vibration belong- 

 ing to this colour has a longitu- 

 dinal position. 



13. The constant (or limiting) 

 tones of colour A and B are con- 

 nected with vibrations ; B in the 

 direction of the axis, A perpen- 

 dicular to it. 



14. In the direction of the axis 

 we see the colour A by vibrations 

 perpendicular to the axis. In a 

 direction pei-pendiculartothe axis 

 we also see the same colour A by 

 vibrations perpendicular to the 

 axis. 



15. Vibrations perpendicular 

 to the axis take place only for 

 the colour A. 



16. Vibrations in the direction 

 of the axis take place only for the 

 colour B. This colour is there- 

 fore invisible in the direction of 

 the axis. 



17. For the colour A the vi- 

 brations take place only perpen- 

 dicular to the axis. 



18. In the mixed tones of co- 

 lour, each colour appears, accord- 

 ing to its api)ropriate direction of 

 vibration, dependent on the co- 

 sine of the inclination of the last 

 with the usual ray, 



1 1 . The same direction of vi- 

 bration is connected with the 

 same tone of colour, only per- 

 pendicular and parallel to the 

 axis. In all other directions it 

 is connected with all possible 

 gradations of colour. 



12. In the direction of the axis 

 we do not see the colour B, 

 although the vibrations belong- 

 ing to it take place in all azi- 

 muths perpendicular to the axis. 



13. The constant tones of co- 

 lour A and B are connected with 

 vibrations ; B perpendicular to 

 the axis, A parallel to it, perpen- 

 dicular to it, and making all in- 

 termediate angles with it. 



14. In the direction of the axis 

 we see the colour A by vibrations 

 perpendicular to the axis. In a 

 direction perpendicular to the 

 axis we see the same colour A by 

 vibrations parallel to the axis. 



15. Vibrations perpendicular 

 to the axis take place for A, B, 

 and every intermediate colour. 



16. Vibrations perpendicular 

 to the axis take place for the 

 colour B, notwithstanding this 

 colour is invisible in the direc- 

 tion of the axis. Just such 

 vibrations, however, take place 

 for the colour A, and yet this 

 colour is visible in the direction 

 of the axis. 



17. For the colour A, the vi- 

 bration takes place in all azi- 

 muths perpendicular to the axis, 

 in all azimuths along the axis, 

 and in all azimuths of the prin- 

 cipal section. 



1 8. Mixed colours occur with- 

 out a change in the direction of 

 vibration. 



