Dr Seebeck on the refractive powers, $ c . 99 



admit blue rays in greater proportion than those of other peo 

 pie; therefore, when any kind of light is less abundant in blue 

 as is the case with candle-light compared to day-light, our eyes 

 serve m some degree to temper that light, so as to reduce it 

 nearly to the common standard. This seems to be the reason 

 why colours appear to us by candle-light, almost as they do to 

 others by daylight. 



I shall conclude this paper by observing, that it appears to 

 me extremely probable, that the sun's light and candle-light, 

 or that which we commonly obtain from combustion, are ori- 

 ginally constituted alike ; and that the earth's atmosphere is 

 properly a blue fluid, and modifies the sun's light so as to oc- 

 casion the commonly perceived difference. 



Art. XL— O* the relation between the Refractive rowers and 

 the polarizing angles of singly refractive substances. By 



fo^' f EEBECK - TransIated from PoggendorfTs ^„nofei 

 1830, No. 9, p. 27. 



When Mains discovered that a ray of light reflected from the 

 surface of bodies not metallic, possessed the property of beino- 

 polarised like one of the pencils formed by calcareous spar" 

 he sought in vain to discover a relation between the angles at 

 which this property was most completely produced and the 

 other properties of the reflecting body. He observed that the 

 angle of maximum polarization was in general greater with 

 bodies of a great refraction, and that the pencil reflected from 

 both surfaces was simultaneously polarized ; but notwithstand- 

 ing these observations, he expressly says, « I have determined 

 with many substances the angle at which light is completelv 

 polarized, and I have found that this angle follows neither the 

 order of the refractive powers nor that of the dispersive forces. 

 It is a property of bodies independent of the other modes of 

 action which they exercise upon light." 



It must, therefore, have been a matter of great surprise when 

 Dr ^Brewster announced in the Philosophical Transactions for 

 1815, as the results of his measurements, that the angle of 

 maximum polarization is a function of the refractive power of 

 »e reflecting body. This la* he expresses thus : 



