308 Intelligence and Miscellaneous Articles. 



out in the rough result of experiment thus disappear. The results 

 obtained agree exactly with those recorded in my first Note. Max- 

 well*, who has studied the solar spectrum with the greatest care 

 from the physiological point of view, has assigned slightly different 

 positions to the colours which correspond to the fundamental sen- 

 sations, as the following table shows : — 



Maxwell. 



Place in the chromatic Place in the solar 



circle. spectrum. 



Third red ± from C towards D. 



Green | „ E „ F. 



Fifth blue J „ F „ a. 



EOSEXSTIEHL. 



Place in the chromatic Place in the solar 



circle. spectrum. 



Orange f from C towards D. 



Third yellow-green . . . . f „ D „ E. 



Third blue J „ E „ &. 



As rotating disks permit us to experiment with greater precision, 

 I believe these last data to be very near the trutht. 



In brief, taking as a basis the equidistance of the colours which 

 constitute each of the three sections of the chromatic circle, I arrive, 

 by two analytical experimental methods, and without making any 

 hypothesis, at proving that there exist three colours (the exact 

 position of which I have determined) which possess relatively to 

 our eye special properties. I have rigorously defined these proper- 

 ties, which coincide with those accorded by physiologists to the 

 fundamental sensations. Thus the law of the mixture of colours, 

 established a priori by Newton, developed by Young, Helmholtz, 

 and Maxwell, is verified in its principles and specified in its conse- 

 quences. — Comptes Rendus de VAcademiedes Sciences, t. xcii. pp. 357— 

 360 (Feb. 14, 1881). 



OX TONES PRODUCED BY THE INTERMITTENT IRRADIATION OF A 

 GAS. BY W. C. RONTGEN. 



In my lectures on experimental physics I have for some time 

 employed the following apparatus to render visible, in a simple 

 way, the different capabilities of absorbing heat-rays possessed by 

 the gases. 



A glass tube about 4 centims. in diameter and 40 centims. in 

 length, placed horizontally, is closed at both ends with plates of 



* Proceedings of the Ptoyal Society of London, vol. x. p. 404 (1860). 

 t Maxwell, moreover, operated upon only sixteen colours of the spec* 

 trum, which he mixed three by three. 



