( 469 ) 



v.— OF PASSAGES OVER THE NORTH ATLANTIC OCEAN. 



1. GENEEAL EEMAEKS. 



(472.) In the preceding pages we have described those natural phenomena 

 of Winds, Currents, &c,, which govern the track of a ship across the Ocean. 

 The object of the present section is to apply these principles to the sea- 

 man's practice , but, previous to entering upon this portion of the task, 

 we will make a few general observations upon Great Circle Sailing, which 

 has been revived as a new subject, wnen m tact it is one which was among 

 tho earliest principles recoguized in navigation. This is not the place to, 

 enter into disquisitions on the working of Great Circle problems — that 

 must be left to works specially devoted to Nautical Mathematics.* The 

 excellent " Practico of Navigation" by Lieutenant Eaper, or Towson's 

 " Tables to Facilitate the practice of Great Circle Sailing," will be found 

 excellent guides . but still a greater simplicity in the application to ordinary 

 purposes of navigation is a great desideratum. 



Great Circle Sailing was known and acted on very early in the history 

 of navigation. It is more than probable that Cabot, Columbus, Magalhaens, 

 and all the first great navigators were acquainted with the subject ;f but 

 this, it must be remembered, was prior to the knowledge of the principles 

 of finding the longitude. When Gerhard Mercator, in 1569, published a 

 universal map, on the projection now known by his name, a new era com- 

 menced in navigation ; but its true principles were first correctly described 

 by Edward Wright, in 1599. In this projection, the meridians being 

 straight lines parallel to each other, the latitude is distorted and decreased 

 in proportion as these meridians are more distant from each other than the 

 correct difference of longitude would give for that latitude. Consequently, 

 a straight line drawn between any two points on such a plain chart, will 

 give the correct compass bearing, which, if maintained throughout the 

 course by a ship, will lead her from one point to the other. This course is 



' A very complete account of the different methods is given by Mr. G. W. Littlehales, 

 in his illustrated pamphlet " The Development of Great Circle Sailing," published by 

 the United States Hydrographic Office. 1889. 



t It is alluded to directly in a work by fedro Wufiez, in 1537; again, by Pedro de 

 Medina, in 1545, but his system was erroneous, and was corrected by Martine Cortes 

 (or Curtis), whose work, " The Arte of Navigation," was soon after, in 1561, translated 

 out of the Spanish into English, by Richard Eden, and was long the text-book of English 

 seamen. Numerous other works, in which it is correctly and distinctly described, 

 afterwards appeared, as one by Michael Coignet, of Antwerp, in 1581 ; an excellent 

 work by Roderick Zamarano, in 1585, &c. That by this time it was thoroughly recog- 

 nized is evident by John Davis's book, published in August, 1594, called the " Seaman's 

 Socrets ; wherein is Taught the Three Kinds of Sayling — Horizontall, Paradoxall, and 

 Sayling upon a Great Circle." It is also described in Richard Polter's "Pathway to 

 Perfect Sayling," about the same time. After this it is found in most of the old works 

 on Navigation. 



