Magnetic Dip in the United States. . 85 



"not of the carboniferous," and but slightly of " the old red sand- 

 stone groups ;" but the true Silurian^ of Murchison, terminated 

 or capped by the old red sandstone, " bordering the southern livn- 

 its of the state, and in Alleghany county [N. Y.) extending north 

 of the linef and it appears there upon the Genesee river in a stra- 

 tum about six inches thick, containing a large proportion of iron. 

 The settlement of the questions that have arisen concerning the 

 geology of New York, must be regarded as of the highest inter- 

 est to science, and as having removed the greatest obstacle that 

 existed to the successful study of our American geology. Every 

 one may see how unfortunate would have been a difference of 

 opinion on this subject among the geologists in their final report ; 

 how much, instead of promoting the cause of science, it would 

 have retarded its progress, had their energy and talent been de- 

 voted to the support of conflicting conclusions and opinions. 

 The candor of Mr. Hall in deferring to the new and increased 

 evidence presented by the " Silurian system," is worthy of imita- 

 tion ; and this great extension of that class of rocks, in this country, 

 ascertained and identified solely by comparison with the work of 

 Mr. Murchison, the distinguished pioneer of this geological peri- 

 od, will certainly cause him a noble gratification, while it adds 

 lustre and dignity to his labors. 



Art. VIII. — On the Magnetic Dip in the United States ; by 

 Eli AS LooMis, Professor of Mathematics and Natural Philoso- 

 phy in Western Reserve College. 



Messrs. Editors — I have read with much interest the remarks 

 by Prof Locke in the last number of your Journal, and have in 

 consequence been led to review my former magnetic article pub- 

 in Yol. XXXIX, p. 41, I have carefully compared all of Prof 

 Locke's observations with such of my own as have been made 

 in Ohio and Michigan, both those which are given in my former 

 article, and those which I have since made. I have followed the 

 method adopted by Major Sabine in his magnetic survey of Scot- 

 land. The first column in the following table gives the stations 

 of observation ; the second and third give their latitudes and lon- 

 gitudes, taken from Mitchell's large map of the United States, 

 with the exception of places not shown on that map. The Ion- 



