‘1, ¥* 
* * 
Magnetic Dip in the United States. * 3 
oe a. ” 
“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 lim- 
its of the state, and in Alleghany county (N. Y.) extending north 
of the line ;’ and it appears there upon the Genesee river ina 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. 
— 
Arr. VIII.—On the Magnetic Dip in the United States ; by 
Et1as Loomrs, Professor of Mathematics and Natural Philoso- 
phy in Western Reserve College. 
Messrs. E'ditors—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 Vol. xxxrx, 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- 
Situdes, taken from Mitchell’s large map of the United States, 
with the exception of places not shown on that map. ‘The lon- 
