Mechanical Science. 373 



the magnetic lines belonging to the pole situated on the one or 

 other continent, but in many cases the direction is nearly parallel, 

 and sometimes coincident with the direction of these curves. Thus 

 in Asia, the coast from the north of the Persian Gulf is continued to 

 Bombay, parallel to the curve ; the same is the case on the southern 

 coast of China, which, at the south-east, turns to the north with the 

 curve, and the latter follows exactly the direction of the long chain 

 of islands Leou Kiou, Niphon, Jeso, Seghalien, which really form 

 the eastern extremity of the ancient world. 



In North America and elsewhere, M. Necker shows the same 

 association of forms. He then refers to the well-known observation, 

 that the geographical form of the earth is in direct relation to the 

 elevation of the ground that it is, in fact, derived from the lines of 

 intersection made by the constant and uniform surface of the sea, 

 conjointly with the irregular and undulating surface of the solid 

 parts of the globe. Continents, islands, isthmus, &c., are parts 

 bounded by these intersecting lines. It is equally well known now, 

 and is receiving confirmation daily, that the elevation of the earth is 

 determined by the stratification of the mineral masses which com- 

 pose it, that is to say, that the assemblage of inclinations, or systems 

 of inclination, which constitute the elevation, is in constant relation to 

 the direction and inclination of the strata of the earth. It is to those 

 chains of mountains, more or less elevated or extended, from which 

 the inclined parts of a country descend, that the mineral strata also 

 conform ; and we have reason to believe that the axes of each of 

 those chains of mountains, or parallel set of strata, consist of un- 

 stratified masses of granitic or porphyritic rocks, the existence of 

 which is connected with the laws which reign over the stratification 

 of each region. All geologists generally admit that the direction of 

 the strata on different sides of a chain of mountains is sensibly parallel 

 to the direction of the chain itself. 



From these considerations, it would appear, that if there is any 

 analogy between the configuration of the northern continents and the 

 direction of the curves of equal magnetic intensity, an analogy ought 

 also to exist between the magnetic curves and the direction of the 

 strata of which the earth is composed. M. Necker, therefore, pro- 

 ceeds to compare these curves with what is known of the stratification 

 of the earth in the northern hemisphere, and finds a striking coinci- 

 dence in direction. Thus the magnetic curve of 297 seconds traverses 

 Scotland in a direction S.W. to N.E., which is precisely the direction 

 he found the strata of that country to have when he personally ex- 

 amined them. The curve then passes to . Christiana, in Norway, 

 preserving the same direction ; and according to M. Buch, such is 

 the direction of the strata at Christiana. It traverses Sweden, where, 

 according to Hisinger, the N.E. direction of the strata still continues ; 

 but on arriving at the Gulf of Bothnia, the curve changes and turns 

 to the S.E. Here, and further on, correct observations of the direc- 

 tion of the strata are wanting, but the direction of the northern coast 

 of Russia, Lapland from North Cape to the White Sea, which coast 



