AUTHOR'S PREFACE 



IT is the aim of this volume to illustrate the principles 

 of science by applying them to the world we live in, 

 and to explain the methods by which our knowledge of 

 Nature has been acquired and is being daily enlarged. 

 An attempt is made to define the place of physical science 

 in the sphere of human knowledge, and to show the 

 interrelations of the various special sciences. The 

 greater part of the book is occupied by an outline of the 

 more important facts regarding the structure of the 

 Universe, the form, material, and processes of the Earth, 

 and the relations which they bear to Life in its varied 

 phases. Such descriptions must necessarily be brief, 

 and they are consequently apt to appear more dogmatic 

 than the discoveries of science warrant ; but care has 

 been taken to minimise this result. References to 

 original memoirs are given in cases where the facts 

 or theories are not yet fully accepted, and the student 

 is urged whenever it is practicable to read and study 

 these works. 



The Fahrenheit scale of temperature and the British 

 system of weights and measures are used throughout, 

 as these are most familiar to the class of readers 

 expected. 



The division into numbered paragraphs is intended 

 to facilitate the frequent cross-references, which are neces- 

 sary in order to bring out the interdependence of the 

 various departments of Nature. The illustrations are 



