CONTENTS. 



VK.F.FACE, 



PAGE 



ix 



I. ABOUT VOLCANOS AND EARTHQUAKES. ., . I 



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



III. ON COMETS, . . . . . .91 



IV. THE WEATHER AND WEATHER PROPHETS, . . 142 

 V. CELESTIAL MEASURINGS AND WEIGHINGS, . .176 



VI. ON LIGHT. PART I. REFLEXION REFRACTION 



DISPERSION COLOUR ABSORPTION, . . 2l<) 



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, .... 400 



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



XI. ON ATOMS. A DIALOG!)'?, . . ' . 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 YHE ESTIMATION OF SKILL IN TARGET-SHOOTING, 495 



