is POPULAR LKCTrXKS AND ADDRESSES. 



her then position and to leave it protuberant on 

 the remote side of the earth. It is curious that in 

 books of navigation the tendency has been so often 

 spoken of as if that were the effect. An interest- 

 ing correspondence occurred in the columns of the 

 North British Daily Mail about a year ago, in 

 which Newton's theory of the tides was disproved 

 out of Nome's Navigation. Norric, in his work, 

 describes the tendency ; Newton in his theory 

 describes the tendency, but points out that the 

 waters of the ocean are in a state of continual 

 oscillation and reverberation as it were (between 

 two opposite continents, for instance, as between 

 Africa on the one side and America on the other), 

 and that at no one instant does the tendency have 

 static effect according to what has been called 

 " the equilibrium tide." Now it is the imaginary 

 equilibrium tide that is often described as the 

 theoretical tide in books on navigation, though the 

 many readers ,,f these books, with limited inform- 

 al ion as to what was written by Newton, La- 

 place, and Airy, accuse Newton of all the errors 

 they have been taught. 



