CONTENTS. 3t. 



that. "Velocity of Light. Light aliuay* moves in Right Lines. 

 Rarity of Light, Force or Momentum of Light, Mitchell's Expg~ 

 riment. Inquiry ho~jj far we Sun's Magnitude is diminished by tht 

 EmiJ/ion of Light. Light fubjeft to the ordinary Laws of Nature. 

 'Light attracled by the Bolognian Phofphori.The fatne Property 

 in Diamonds, and other Precious Stones. 



C H A i. III. page 185. 

 General View of the Phenomena of Reflexion. 



Bottles do not reflett the Whole of tht Light that falls on them. 

 Law of Reflexion. Reflexion from plane Surfaces. Reflexion from 

 convex Surfaces. From concave Surfaces. Phenomena of Rcflexicn 

 from plane Mirrors 'explained. from convex Mirrors. From con- 

 cave Mirrors. Prominent Image from a concave 'Mirror.- Tht 

 cylindrical Mirror. The Rectification of dijlorted Figures by this 

 Mirror. The conical Mirror. 



CHAP. IV. page 200. 

 General View of the Phenomena of Refraction. 

 Laws of RefraEiion. Degree of RefracJion which Light fujfers froit 

 different Mediums. Common Phenomena of Refraflion. RefraQiox 

 by j'pherical Surfaces By convex Surfaces By concave Surfaces 

 Of Lenfes. Convex Lenfes. Concave Lenfes. Different Refran- 

 gibility of the Particles of Light. Experiment vjitb the Prifm. 



CHAP. V. page 216. 

 Of the Principles of Catoptrics. 



Places cf Images in plane Rffleclors. Why a Mirror only Half 'the . 

 Size of an ObjeS exhibits a perfefl Image of the Whole. Place* 

 of Images made from Reflexion by fpherical Surfaces. Mode of de- 

 termining the Foci of refleaed Rays from fpherical Surfaces. S;zt 

 and Proportions of Imc.ges in fpherical Refleclors. Phenomena, cf 

 (oncave and convex Speculum! explained. 



CHAP. VI. -page 227. 

 Of tlie Principles of Dioptrics. 



Dioptrics relate to tbt Ejf'efts of Refraftion.In what M&nntrto find 

 the actual Situation of an Object feen in a different Medium.-^^The 

 apparent Situation of an Objerf feen through a Glafs Window dif' 

 fcrent from the real one. The Ejfecls of tranf parent Media nJoitb 

 fpherical Surfaces on the Rays of Light which are tranfmitted through 

 them. Rules for finding the Focus of Rays pajfmg through fuch Me- 

 diums \ Theory of Lenfes. ^Plano-convex and plano-concave Lenfes. 

 Rulee to flnd the Focus of a Lens. -Focus of diverging Rajs in- 

 tercepted to a Lent. Focus of a Sphere. 



CHAP. 



