CONTENTS 



CHAPTER I. 



PROPAGATION OF LIGHT. 



Page. 



(1, 2) Distinction of bodies 'with respect to light ; Vision. (3) Light 

 emanates from luminous bodies in all directions. (4) Non-luminous 

 bodies transparent and opaque. (5) Light is propagated in right lines ; 

 ray of light. (6) Intensity of light emanating from a luminous point 

 varies inversely as square of distance. (7, 8) Measure of illumina- 

 tion; photometry. (9, 10) Velocity of light determined by eclipses 

 of Jupiter's satellites by aberration of fixed stars. (11) M. Fizeau's 

 experimental determination of velocity of light. ( 12) Two theories of 

 light, Des Cartes and Newton ; Hooke and Huygens. (13) Impulse 

 of light insensible. (14) Uniform velocity of light inconsistent with 

 theory of emission. (15) Rectilinear propagation of light apparently 

 opposed to wave-theory not really so. (16) "Wave-propagation ex- 

 plained. (17, 18) Mathematical laws of vibratory movement. (19) 

 Lights differ from one another in intensity and colour ; law of inten- 

 sity. (2,0) Colour of light varies with length of wave ; limits of sen- 

 sibility of the eye. (21) Aberration of light physically explained, . 1 



CHAPTER II. 



REFLEXION AND BEPKACTION. 



(22, 23) Reflexion of light twofold ; law of reflexion. (24) Laws of inten- 

 sity of reflected light. (25, 26) Law of refraction; refractive index. 

 (27, 28) Light traversing media bounded by parallel planes. (29-31) 

 Deviation of ray refracted by prism deduced. (32) Refractive index 

 determined experimentally. (33) Newton's explanation of the laws of 

 reflexion and refraction. (34, 35) Hypothesis of the^s; its insuffi- 

 ciency. (36, 37) Laws of reflexion and refraction deduced from the 



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