PEEFACE. 



* A TREATISE on tlie Action of Vis -Inertia in the 

 Ocean,' published in 1868, was, in some measure, 

 a second edition of ' The Elements, or an Investi- 

 gation of the Forces which determine the position 

 and movements of the Ocean and Atmosphere,' 

 published in 1866 ; and the first edition of this 

 present work, published in 1873, was, to a great 

 extent, a third edition of the same, revised and partly 

 re-written. 



This second edition of ' The Ocean ' has been 

 abridged by the omission of some chapters which 

 have been republished in ' The New Principles of 

 Natural Philosophy,' and minor omissions of matter 

 not closely connected with the subject, and more 

 fully treated in the work just mentioned. Book X., 

 which in the first edition professed to offer merely 

 ' suggestions ' as to the action of Vis-Inertiai in the 



