XIV INTEODUCTIOX. 



labour. Officers here have been engaged upon tbe ^vork for many 

 years. This patient industry has been rewarded with the discovery 

 of laws and the development of truths of great value in navigation 

 and very precious to science. 



It would be presumptuous to claim freedom from error for a 

 work hke this : true progTess consists in the discovery of error 

 as well as of truth. But I may be pardoned for saying that the 

 present edition of this w^ork mil be found to contain more of truth 

 and less of error than any of its predecessors, simply because it is 

 founded on wider research, and based on the results of more abun- 

 dant observations than they. Indeed, it could not, or, rather, it 

 should not be otherwise ; for, as long as we are making progress 

 in any field of physical research, so long must the results continue 

 to increase in value ; and just so long must what at first was con- 

 jecture grow and gain as truth, or fade and fall as error. 



The fact seems now to be clearly estabhshed that the atmosphere 

 is very unequally divided on opposite sides of the equator, and that 

 there is a mild climate in the unkno^vn resfions of the antarctic 



o 



circle. Over the extra-tropical regions of our planet, the atmosphere 

 on the polar side of 40'^ N. and 40^ S. is so unequally divided as 

 to produce an average pressure, according to the parallel, of from 10 

 to 50 lbs. less upon the square foot of sea surface in southern than 

 upon the square foot of sea smface in northern latitudes. These, 

 and many other developments not less interesting, seemed to call 

 for a recast of the work. Indeed several new chapters have been 

 added to this edition, and many new subjects have been treated of in 

 it. New ^dews also have been presented, and the errors of former 

 views corrected wherever in them farther research has pointed out 

 error. These researches have gTo^sm so wide that they comprehend 

 not only the physics of the sea, but they relate extensively to its 

 meteorology also ; hence the present title. The Physical Geogba- 



PHY OF THE Sea, and its METEOKOLOaY. 



1 Albemarle Street, London. 

 20tJi November, 1860. 



