Wm. A. Norto?i on the Variations, fyc. 35 



to be proved [that is, I presume, only] by its resemblance to ma- 

 rine formations and its containing marine relics, 7 — as far as the 

 latter term is concerned. The terraces which I have spoken of 

 as ancient sea margins do, in many instances, present such an 

 arrangement of water-worn materials as might be expected on a 

 coast. In many cases, there is no decisive feature of this kind, 

 or I have not been able to ascertain particulars. On this point I 

 am hopeful of seeing much new light as the investigation pro- 

 ceeds, particularly if I may believe that M. Morlot, of Vienna, is 

 not deceived in thinking, as he informs me, that he jean distin- 

 guish sea from river pebbles. With regard, however, to marine 

 relics, I think the importance which Mr. Dana attaches to them 

 is unduly exclusive. It might even be that they would prove a 

 fallacious guide in the present enquiry, as indicating only the 

 general fact of a former presence of the sea (for which indication 

 they are in a manner superfluous), and not the special fact that 

 the spot where they were found was a margin of the sea. In 

 the climate of Scotland, it is quite hopeless that shells should be 

 preserved in a porous bed for a great length of time, and I am not 

 therefore surprised that no such relics are found in any but com- 

 paratively recent sea margins. But if we find other proofs, as in 



exa 



beaches, the character and arrangement of inorganic materials, 

 and identity of levels over a wide area, (a kind of proof the 

 most rigid of all, being mathematical,) are we to hold them as 

 nought merely because we lack a kind of proof which is not 

 reasonably to be expected in the case ? Against such reasoning 

 I must enter my humble, but energetic protest. And I believe 

 that Mr. Dana, ongoing into a practical investigation, would very 

 quickly justify me in doing so. 



Let me conclude with the expression of a hope that some of 

 the American geologists will ere long go into the enquiry with 

 more or less rpo-ard tr> thp mips laid down bv Mr. Dana. 



Art. IV.— On the Diurnal Variations in the Declination of the 

 Magnetic Needle, and in the Intensities of the Horizontal 

 and Vertical Magnetic Forces; by William A. Norton, Pro- 

 fessor of Mathematics and Natural Philosophy in Delaware 

 Coll 



ege. 



Is 



« -ition of a new theory of Terrestrial Magnetism, of which 

 the following are the fundamental principles: 1. Every particle 



Pages 1 to 12 and 207 to 230. 



