146 MAGNETIZATION OF LIGKT. 



with which the hour can be readily determined by examin- 

 ing the polarized condition of the sky. It has been stated, 

 that chemical change on the Daguerreotype plates and on 

 photographic papers is more readily produced by the 

 polarized than by the ordinary sunbeam.* If this fact 

 be established by future investigations, we* advance a 

 step towards the discovery so much desiderated of the 

 part it plays in natural operations. 



The refined and accurate investigations of Dr. Fara- 

 day stand prominently forward amid those which will 

 redeem the present age from the charge of being super- 

 ficial, and they will, through all time, be referred to as 

 illustrious examples of the influence of a love of truth 

 for truth's sake, in entire independence of the market- 

 able value, which it has been unfortunately too much 

 the fashion to regard. The searching examination made 

 by this " interpreter of nature " into the phenomena of 

 electricity in all its forms, has led him onward to trace 

 what connexion, if any, existed between this great 

 natural agent and the luminous principle. 



By employing that subtile analyzer, a polarized ray, 



* On the Polarization of the Chemical Kays of Light: by 

 John Sutherland, M.D., in which the author refers to the follow- 

 ing experiment of M. J. E. Berard " I received the chemical 

 rays directed into the plane of the meridian on an unsilvered glass, 

 under an incidence of 35 61. The rays reflected by the first glass 

 were received upon a second, under the same incidence. I found 

 that when this was turned towards the south, the muriate of silver 

 exposed to the invisible rays which it reflected was darkened in 

 less than half an hour; whereas, when it was turned towards the 

 west, the muriate of silver exposed in the place where the rays 

 ought to have been reflected, was not darkened, although it was 

 left exposed lor two hours. It is consequently to be presumed 

 that the chemical rays can undergo double refraction in traversing 

 certain, diaphanous bodies; and lastly, we may say that they enjoy 

 the some physical properties as light in general." Philosophical 

 Magazine, vol. xx. 



Dr. Leeson has stated that Daguerreotype pictures can betaken 

 more readily under the influence of polarized light, than by ordi- 

 nary radiation. 



