xii CONTENTS. 



SOUND. 



PAGE 



1. Definition. 2. Air the conductor. 3. Sound progressive. 4. 

 Breadth of sonorous waves. 5. Musical sounds, how charac- 

 terised. 6. Pitch. 7. Loudness. 8. Timbre. 9. Velocity. 

 10. Distances measured by sound. 11. Density of air affects 

 loudness. 12. Effect of atmospheric agitation. 13. Sound 

 conveyed through liquids. 14. Solids. -15. Effects of elasticity 

 of air. 16. CWadni's experiments. 17. Monochord. 18. 

 Vibration of musical strings. 19. Cause of harmony shown . 185 



The numbers of the paragraphs and figures of tlie " PRE-ADAMITE 

 EARTH," are continuous with those of the " CRUST OP THE EARTH," in- 

 -volume XI., of which subject the "PRE- ADAMITE EARTH" is the con- 

 tinuation and development. This statement will explain what might 

 otherwise seem incorrect in the numbering of the paragraphs and fgures. 



ERRATA. 



Pre- Adamite Earth, page 85, paragraph 362, line 2, for "160," read " 163." 

 page 86, line 10, for " Equitaceae," read " Equisetaceai." 



