PREFACE 



TO THE THIRTEENTH EDITION. 



-;o:- 



MoBE than sixty years have elapsed since the First Edition of this work 

 made its appearance— a period which has witnessed a total change in the 

 aspect and requirements of Hydrography, as in most other departments of 

 knowledge. 



Professing to deal with the subject in its present condition, this Edition 

 bears no resemblance to the book in its original form, except in the title it 

 bears ; every topic and every page have been changed by the accession ot 

 facts, due to the research which modern refinement brings to bear upon 

 every branch of scientific enquiry. 



There has been no greater advance made during any portion of the long 

 time which has elapsed, since its first appearance, than has taken place 

 during the last twenty years ; and, to represent that advance, this Edition 

 has been entirely remodelled, and may be considered rather as a new work 

 upon the former arrangement, than as a revised production. 



The examination of the bottom of the Ocean, almost a new subject 

 and yet in its infancy, has already dispelled many of those dangers which 

 were formerly believed to exist. The various features which have been 

 elucidated in the Wind and Current systems, and their bearings upon the 

 best Routes for traversing the Ocean ; the more exact acquaintance with 

 the Magnetical condition of the Earth, and the most important connection 

 this has with the increasing number of iron ships ; with many other 

 subjects, will be duly discussed in the ensuing pages. 



To enumerate here the authorities to which we are indebted would be 

 to offer a long list : we have duly acknowledged them throughout the 

 work ; and we trust that this Thirteenth Edition may do as good service 

 to the mariner in its quiet utility, as those which have preceded it. 



A. G. FiNDLAY. 



London, February, 1873, 



The foregoing Preface may be said to apply equally to this Fifteenth 

 Edition, in its reference to the rapid increase in our knowledge of the 

 Ocean and its shores. In 1879 the Fourteenth Edition was issued, care- 

 fully revised, with numerous additions bringing it abreast of that datt.; 



N.A.O. ■ j« 



