8 PREFACE 



of a storm at sea, the second is the surf which comes 

 in during calm weather upon a shore facing the 

 open ocean, the breakers booming like minute guns. 

 The first indicates the fury of the wind, but it is 

 the second which we almost instinctively recognise 

 as affording the best index of the greatness of the 

 expanse of water. 



These things, and others of a like nature, I have 

 watched for many years, and I have set down in 

 this book what I have been able to add to former 

 knowledge. 



I have written to inform the mind, not to stir the 

 imagination. The appearances are familiar and 

 recurrent, and I do not attempt to recall them by 

 much word-painting, but the precise observation 

 and measurement of waves, and the discovery of 

 the mode of their production, are matters of 

 difficulty, and to these I have given myself. 



My investigations pn water waves have been 

 prosecuted during the last fifteen years. They have 

 been made in many parts of the world^ which I have 

 visited principally for the study of surface waves 

 of different kinds. The chief results as far ;as 

 they relate to water waves are contained in this 

 volume, which contains also a critical examination 

 of observations made by a number of seamen and 

 others upon the size and speed of ocean waves. 



