SUPPLEMENT 
21 
be sought for, and which exactly corresponds with the discoveries 
detailed by Commander Ross, in his memoir to the Royal 
Society. According to that most erudite mathematician, the 
north magnetic pole seems to be situated near to the meridian, 
which passes by Cape St. Lucar, the south point of California, 
and between the latitudes of 70° and 80° north. 
The situation of the south magnetic pole at that time seems 
to have been above 60° more westwardly, and near the latitude 
of 60° south. 
From the position of the magnetic poles, the result is as fol¬ 
lows :—From the north magnetic pole a line of no declination 
commences, and by a route somewhat resembling the letter S, 
it traverses the continent of North America and the Atlantic 
Ocean to the south pole of the earth, and then, by the arc of 
180°, to the south magnetic pole. 
From the south magnetic pole this line of no declination pro¬ 
ceeds, and in like manner traversing the Pacific Ocean passes 
by the islands of the East Indies, and through the continent of 
Asia to the north pole of this earth, and so by the little arc of 
180° to the north magnetic pole. 
These lines divide the surface of the globe into two parts, 
and in going eastward from the first to the second line over the 
eastern parts of North America, Europe, Africa, and a great part 
of Asia, there is west declination ; but from the second to the 
first, over the eastern parts of Asia, South America, the western 
parts of North America, and the Pacific Ocean* there is east de¬ 
clination. The declination of the lines of the second order cor¬ 
responding to the greatest equatorial declination, amounts in this 
case to 12° ; and for the east declination they cross one another 
in north latitude 24°, and about 30° in longitude west of the me¬ 
ridian of California ; for west declination, the intersection is 
likewise in 24° north latitude, upon that part of the coast of 
the Red Sea which is next to Arabia Felix. 
That line, which we shall call the Atlantic line of no declin¬ 
ation, seems to take its origin from the north magnetic pole, and 
crossing the different meridians in a south-easterly direction, re¬ 
sembling in form the long letter S, it traverses the continent of 
