Geological Survey of the State of New York. 95 
current, therefore, setting down from the ocean into the bay, 
must prevail during the six hours of depression ; and an equally 
strong current setting down from the bay into the ocean, must 
prevail during the same period of elevation. Granting these con- 
ditions, we should be authorized, on the principles of hydrody- 
namics, to expect tides of eutrecndinates height at the eastern an- 
gle of the bay, and that a reflex influence would be experienced 
along the line of coast westward. Were the position of the Bay 
of Fundy reversed, so that it should open easterly into the At- 
lantic, all that is citeaatianene’ in the phenomenon we have been 
considering would probably disappear. 
~ The possible bearing of our argument on the subject of mag- 
netic polarity, is sufficiently obvious. If the magnetic line at 
any given place is the resultant of all the magnetic influences in 
the body of the earth, then whatever cause affects the figure of 
the earth will affect the position of the magnetic line. Whatever 
the causes of the subordinate oscillations of the needle may be, 
it is not doubted that they are connected with the diurnal me 
annual motions of the earth. Admitting then the existence of 
internal tides, there is no absurdity in the supposition, that the 
distribution of the magnetic influences may be so far affected by 
them as to impart to the needle a sensible irregularity, whose pe- 
riod shall be a lunar day, and whose amount shall vary monthly 
and annually, according to the different relative positions of the 
moon, the sun, and the earth. It may not therefore be a matter 
devoid of interest, to settle by accurate observation, whether the 
minor oscillations. of the magnetic line be or be not connected; 
in ee epee, with the lunar motions. 
‘Hamilton College, May 10, 1540, er 
Arr. XIII.— Notice of * Third Annual Reports on the Geological 
Survey of the State of New York, to the Assembly, Document 
275, Feb. 27, 1839;” by Oxrver P. Husparp, M. D., Professor 
ce = eccisiry. Mineralogy and Geology in Dartmouth College, 
New Hampshire. 
Tue Report of 1838 received an extended notice in this Jour- 
nal, Vol. xxxvr, p. 1, in which the results of the labors of the geol- 
ogists were fully exhibited. The Report of 1839 need not ce. 
