CONTENTS. 



PAGB 



PREFACE, . , , . . . Vii 



I, ABOUT VOLCANOS AND EARTHQUAKES, . , I 



II. THE SUN, . . . , . .47 



III. ON COMETS, . , , . .91 



IV. THE WEATHER AND WEATHER PROPHETS, . . I42 



V. CELESTIAL MEASURINGS AND WEIGHINGS, . . I76 



VI. ON LIGHT. PART I. REFLEXION REFRACTION 



DISPERSION COLOUR ABSORPTION, . . 219 



VII. ON LIGHT. PART II. THEORIES OF LIGHT INTER- 

 FERENCES DIFFRACTION, .... 268 



VIII. ON LIGHT. PART III. DOUBLE REFRACTION POL- 

 ARIZATION, .,,... 340 



IX. ON SENSORIAL VISION, .... 4OO 



X. THE YARD, THE PENDULUM, AND THE METRE, . 419 



XI. ON ATOMS. A DIALOGUE, . * . 452 



XII. ON THE ORIGIN OF FORCE, .... 460 



XIII. ON THE ABSORPTION OF LIGHT BY COLOURED MEDIA, 

 VIEWED IN CONNEXION WITH THE UNDULATORY 



THEORY, ...... 476 



XIV. ON THE ESTIMATION OF SKILL IN TARGET-SHOOTING, 495 



