THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



SUPPLEMENT to VOL. XXX. THIRD SERIES, 



LXXII. On the Plicenoviena exJiihited by Polarized Light when 

 its j)lane of i^olarization is rapidly rotated. By Professor 

 Dove*. 



A S unpolai'izecl light exhibits the same physical properties 

 ■^^ in all planes throughout the ray, whilst in rectilinearly 

 polarized light these are diiferent in the different planes, and 

 attain their maxima and minima in two planes situated at right 

 angles to each other, and gradually pass into one another by 

 intermediate stages in those which lie between them, the 

 question arises, what will be the properties of polarized light 

 the plane of polarization of which is put into rapid rotation. 

 The experimental answer to this question gives rise to very 

 numerous phoenomena, which illustrate in a remarkable man- 

 ner several positions in the theory of light, which have as yet 

 been only theoretically investigated. 



Two supports of the same height as the other supports were 

 placed to the triangular prism of the polarizing apparatus, 

 described by the author in the Scientific Memoirs, vol. i. p. 86, 

 in the fixed rings of which, hollow rollers could be set in rapid 

 rotation by a band passing round a wheel with two grooves. 

 Both the rollers can rotate in the same direction, and, by 

 crossing one of the bands, in the opposite direction. Within 

 and on both sides of the hollow rollers, Nichol's prisms, cir- 

 cularly polarizing plates of mica or ground crystalline plates 

 can be screwed. The condensing lens of the apparatus is so 

 placed as to concentrate the light of an Argand or monochro- 

 matic lamp in the polarizing apparatus, whether at rest or in 

 rotation. The results of the experiments were as follows : — 

 1. Light which is completely polarized rectilinearly when the 

 Nichol's prism is at rest, possesses exactly its ordinary pro- 

 perties wiien it is set in uniform rapid rotation, if the analy- 

 sing apparatus is not rotated. On examination by a doubly 



• Translated by Dr. Griflitli from the DericlUc der Berliner Akadcmie for 

 Feb. 1847. 



Phil. Mag. S. 'J. No. 20i. Suppl. Vol. 30. 2 I 



