CONTENTS. 
CHAPTER L 
PAGE. 
The Constitution of Nature 1 
CHAPTER II. 
Radiation v '. 20 
CHAPTER III. 
On Radiant Heat in Relation to the Color and Chemical Constitu- 
tion of Bodies 54 
CHAPTER IV. 
New Chemical Reactions Produced by Light 71 
CHAPTER V. 
The Sky 98 
CHAPTER VI. 
Voyage to Algeria to Observe the Eclipse 107 
CHAPTER VII. 
Niagara 132 
CHAPTER VIII. 
The Parallel Roads of Glen Roy 155 
CHAPTER IX. 
Alpine Sculpture 175 
CHAPTER X. 
Recent Experiments on Fog-Signals 193 
CHAPTER XL 
On the Study of Physics 215 
