xii Contents. 



merits changed Nebular hypothesis The sun 

 cool, luminous, and habitable Celestial spectro- 

 scopy Undulatory theories ignored Light instan- 

 taneously transmitted Telephone No light nor 

 heat wasted Extent of the atmosphere of the 

 spheres The sun's power overestimated. 



CHAPTER XIII. 



INFLUENCE OF THE FORCES AS CAUSATION OF DIS- 

 EASE 84 



Meteorological influence Higher appreciation of the 

 source of disease, and increased efficiency in its 

 treatment. 



CHAPTER XIV. 



THE ARTIFICIAL PRODUCTION OF LIGHT, HEAT, 

 AND POWER, AND THEIR UTILIZATION 87 



CHAPTER XV. 



WHY WAS NOT THIS DISCOVERY SOONER MADE ? 90 



Its consummation nearly perfected by many others 

 Its successful accomplishment plainly foretold by 

 Faraday. 



APPENDIX 95 



