62 Analyses of Books. [Jan. 



double Touch ; of the Influence of Temperature upon the Deve- 

 lopment of Magnetism ; of the best Form for Compass Needles ; 

 of the Action of Loadstones upon all natural Bodies ; Laws of 

 terrestrial Magnetism at different Latitudes. 



The fifth book is on Light : it is divided into the three parts 

 of catoptrics, dioptrics, and the analysis of light. Under 

 catoptrics we have the general Laws of the Reflection of Light ; 

 of the plain Mirror ; of curved Mirrors ; of the Heliostate, and 

 general Considerations on the Forces which produce the Reflec- 

 tion of Light at the Surface of Bodies. Under dioptrics we have 

 general Laws of simple Refraction ; of spherical Lenses ; phy- 

 sical Theory of Refraction ; of double Refraction ; Construction 

 of Micrometers with double Images. The analysis of light em- 

 braces the following Topics : of the Dispersion of Light produced 

 by Refraction ; Influence of the unequal Refrangibility of the 

 Rays upon Vision across refracting Surfaces ; of Achromatism. 

 In a sequel to the subject of dioptrics we have six chapters on 

 the following subjects : on the Reflections, Refractions, and 

 Colours, of thin transparent Bodies ; on the Fits of easy Re- 

 flection and easy Transmission ; Application of the preceding 

 Theory to the Reflection of the Rays of Light which have 

 crossed thick Media; Explanation of permanent Colours of 

 Bodies ; on the Return of Rays reflected by Plates with plain 

 and parallel Faces ; on the Return of Rays by curved Plates ; 

 Explanation of the coloured Crowns which appear round the 

 Stars ; on the Colours produced by many successive Reflections ; 

 what takes place when Colours reflected or transmitted by thin 

 Plates seem to emanate from their Substance . 



The polarization of light is become quite a new science, and 

 accordingly forms the subject of the sixth book. The following 

 are the titles of the chapters that compose it : general Proceed 

 ings by which we produce permanent Polarization; of the Periods 

 in which Polarization is produced and completed in crystallized 

 Bodies possessing double Refraction ; of the Colours given by 

 thin crystallized Plates, when we present them to Rays under 

 certain Incidences ; experimental Laws of these Phenomena ; 

 oscillatory Motion of the Axis of Polarization deduced from the 

 preceding Phenomena ; Examination of the Modifications expe- 

 rienced by the Molecules of Light, when they cross many 

 Plates in Succession, which produce the moveable Polarization ; 

 Processes which result from them to develop coloured images in 

 thick Plates by the crossing of their Axes ; of the physical Pro- 

 perties which the Molecules of Light assume in the Interior of 

 Crystals ; critical Examination of the Phenomena produced 

 under oblique Incidences by Laminae and Plates parallel to the 

 Axis of Crystallization ; Experiments upon Plates of Rock 

 Crystal cut perpendicularly to the Axis of Crystallization ; Phe- 

 nomena of successive Polarization observed in homogeneous 

 Fluids ; Examination and Laws of the Phenomena which Plates 



