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VIII: Notices respecting New Buoks. 

 Mature Series. Polarization of Light. By William Spotiswoode, 



M.A., LL.D., F.R.S., $c London : Macmillan and Co. 1874 



(crown 8vo, pp. 129). 

 r PHIS work contains an admirably clear and exact account of the 

 -* phenomena of Polarized Light. The author explains, in the first 

 place, the various ways in which light is made to undergo the pro- 

 cess of plane polarization (by passage through a doubly-refracting 

 crystal and by reflexion and refraction by glass), and then describes 

 the double-image prism, Nicol's prism, and Norremberg's apparatus. 

 The subjects of the interference of plane-polarized light, the me- 

 thods of producing circularly polarized light, and the interference 

 of circularly polarized light are next discussed at considerable 

 length with reference to pencils of parallel rays. These subjects 

 fill two thirds of the volume; but, as well as the main subject, several 

 collateral points of great interest come under notice in the course 

 of the discussion : such are the various forms of the saccharometer, 

 Sir C. Wheatstone's apparatus for producing circularly polarized 

 light by reflexion at a metallic surface, and exhibiting the effects 

 of passing light in that state through crystal films, the phenomena 

 resulting from the action on polarized light of glass when unequally 

 cooled, or when in a state of stress, the phenomenon of atmospheric 

 polarization, the polar clock, &c. The student who has made 

 out this part of the volume will be able to understand easily the 

 account which follows of the results arising from the use of a pencil 

 of divergent rays, and the beautiful phenomena of coloured rings 

 produced by the action of various crystals on such a pencil. In 

 several places the author notices the results of an examination of 

 the spectrum of the pencil of interfering light which issues from 

 the analyzer ; and a good deal of attention is paid to the produc- 

 tion of complementary colours by polarized light. In fact the last 

 chapter of the volume is a reprint of the author's paper "On 

 Combinations of Colour by means of Polarized Light," origi- 

 nally published in the ' Proceedings of the Hoyal Society,' vol. xxii. 

 p. 354. 



It will be seen from the above brief account of its contents that 

 the work before us passes in review all the main points of interest 

 in the subject. The author speaks of his book as " a talk rather than 

 a treatise on polarized light," and says that it contains " the sub- 

 stance of lectures delivered at various times to my work-people." 

 It is therefore so far a popular book, that the subject is discussed 

 without the aid of mathematical symbols ; and doubtless, when the 

 experiments described were actually exhibited, the lectures would 

 be very interesting to any intelligent audience. This, however, 

 does not prevent the book from being decidedly hard reading ; and 

 it would be easy to point out passages which could not be fully 

 understood by a reader wholly without the mathematical learning 

 which the author has at command. On the other hand, a reader 

 who already has some acquaintance with the mathematical treat- 

 ment of the subject will find the time usefully spent which he de- 



