Prof. W. A. Norton on Terrestrial Magnetism. 207 



day, close at the water's edge, I saw that they appeared to be con- 

 tinued beneath the stream. But on close examination I found 

 quite a deposit of mud above the rock, and on this mud the cur- 

 rent had formed ripple marks very similar to those upon the 

 stone. The rounded masses of trap, which enter into the com- 

 position of the tufaceous conglomerate, also, must have been 

 swept southerly. 



valley appears 

 and to nearlv t 



same 



C" ~> ~~ * *«~WV VX^VUfUAUU. *V WIU « XXX XXX J M. XXXVUM. *~^^*» 



J Geology of Massachusetts. If so, it must have presented 

 currents moving from the west shore to the eastward, so as to 

 carry materials for rocks across the entire valley, even if each 

 shore had not been entirely above the waters. Yet we find in fact 

 that the coarsest materials were deposited latest ; that is, on the 

 east side of the valley ; but as the sides of the valley rose higher 



current 



weaker and weaker ; whereas, that elevation might have made a 



current 



In the fourth place, a dip from 10° to 20° is too great to be 

 the result of deposition, where the materials are very fine, as in 

 the present case, and where they are spread with great evenness 

 over large surfaces. Unless in peculiar circumstances, plastic 

 materials cannot be retained on such a slope. 



Finally, in the elevation and plication of the Hoosic or Green 

 Mountain range, lying west of the valley, it may be by a lateral 

 force, we have an adequate cause for the elevation of the sand- 

 stone. This will explain the uniformity of its dip through the 

 whole valley, and its existence even on the eastern border of the 

 Valle y- It appears to me, therefore, more in accordance with 

 sound geological reasoning, to regard these sandstone strata as 

 tuted up by some of those later movements, probably by lateral 



ranges 



Appalachian 



***• XYlII._Ow Terrestrial Magnetism; by William A. 

 Norton, Professor of Mathematics and Natural Philosophy m 



Del 



aware College. 



(Concluded from p. 12.) 



Declination of the Magnetic Needle. 



The first computation was of the declination for London, as- 

 ^ng the poles of greatest cold to be coincident with the mag- 

 pie poles. The result was a declination a number of degrees 

 l °o small. After two or three trials I found that by placing hy- 



