70 
Dutton. ] ‘ [April 7, 
Mr. Walker, in his Adams Prize Essay for 1865, p. 268, says: ‘it is 
worthy of remark that the portion of the year when the magnetic force is 
the greatest, and the direction of the needle most vertical in both hemis- 
pheres, coincides with that at which the earth is nearest to the sun and 
moves with the greatest velocity in its orbit. This fact furnishes another 
argument against the theory that these effects are due to temperature, as 
in that case they ought to occur at opposite periods of the year in the two 
hemispheres, whereas in fact they occur at the same period in both.’’ The 
writer was doubtless misled by the annual variations in declination and 
horizontal force, which are evidently dependent upon the relative tem- 
perature of the northern and southern hemispheres. But if all the 
magnetic effects are primarily due to thermal and gravitating motion, it 
is evident that the tota/ magnetic foree must depend upon the total cur- 
rent producing energy of the sun, which is, of course, a maximum when 
“the earth is nearest the sun, and moves with the greatest velocity in its 
orbit.” The argument which was considered conclusive against the the- 
ory, is, therefore, wholly in its favor. 
Tue cAusES oF Regional Elevations and Subsidences, by Lirur. C. E. 
Duron. 
(Read before the American Philosophical Society, April 7, 1871.) 
Lieut. C. E. Dutton, desired to submit certain views, which he had 
been led to entertain, respecting the causes of regional elevations and 
subsidences. He was unacquainted with any views on this subject in the 
writings of geologists, which seemed to be satisfactory. In reflecting 
upon the nature of metamorphic rocks, and the probable changes which 
they had undergone, he thought that the facts brought to light by the re- 
searches of Bischoff, Daubrée, Sorby, Sterry-Hunt and others in that 
field, might contain, also, a solution of the unexplained problem of ele- 
vations and subsidences. It is now a generally accepted opinion among 
writers upon chemical geology, that metamorphic rocks have reached their 
present, condition, through the combined agencies of heat, pressure, and 
water, acting upon sedimentary strata; that sulphur, carbonic acid and 
yolatile chlorides and fluorides have played highly important parts under 
similar conditions, and that soluble earths and metallic salts and vapors 
have had no inconsiderable influence upon the totality of changes, That 
water especially, under the influence of a moderately high temperature 
and great pressure, is capable of changing in a wonderful manner the 
structure and arrangement of rocky materials of all kinds, has been abun- 
dantly shown by innumerable synthetical experiments, a great number of 
which have been summed up by Daubrée in an able memoir on the sub- 
ject to the French Academy. He has also shown that minerals, which, 
