276 Prof. Norton on Molecular Physics. 



electric aether that pervades the earth's crust, and thus originate 

 the currents supposed, the consequent effects upon the decli- 

 nation and horizontal force should be of the same character, 

 if not of equal amount, at midnight and at noon. Besides, 

 the moon by this sort of action should produce greater effects 

 than the sun. The moon, as a matter of fact, does exercise 

 a disturbing action upon the magnetic needle, but the pertur- 

 bations produced by it have only been detected by the closest 

 scrutiny. 



We may here take occasion to remark that the lunar-diurnal 

 variations of the declination and of the horizontal force are, in 

 their nature, such as should result from a tidal action of. the 

 moon upon the terrestrial sea of electric aether. Thus there 

 should be theoretically a maximum of west declination at the 

 upper culmination, or thereabout, and another maximum at the 

 lower culmination. There should also be a maximum of hori- 

 zontal force a few hours after each culmination, and a minimum 

 a few hours before each culmination ; for the rise and fall of 

 the electrical tide should be attended with currents, or rather 

 waves of translation, setting from all directions toward the point 

 underneath the moon, or a point somewhat in advance of this, 

 and also toward the diametrically opposite point. 



Secular Variations. — The secular changes experienced by the 

 declination and directive force of the needle appear to be the 

 natural consequence of the continual operation of the physical pro- 

 cess by which the earth was originally magnetized. It will be 

 recollected that this consists principally in the development of 

 ecliptic currents on the side of the earth furthest from the sun, 

 which have a greater intensity than the oppositely directed cur- 

 rents developed on the side toward the sun ; also that these pre- 

 ponderating currents which originated at any station at the sol- 

 stices run from E. to W., while those developed at the vernal 

 equinox proceed from S. of E. to N. of W., and those developed 

 at the autumnal equinox from N. of E. to S. of W. It is also to 

 be observed that, in the northern hemisphere, the currents which 

 originate at the autumnal equinox exceed in intensity or quantity 

 those which originate at the vernal equinox, for the reason that a 

 greater portion of each northern parallel of latitude is exposed to 

 the impulsive action of the aether. Now conceive all the cur- 

 rents in question that originate during the year at any station 

 to be decomposed into two, one running from E. to W., and the 

 other from S. to N. or from N. to S. It will be seen that the 

 annual resultant of the one set of components will constitute a 

 current from E. to W., which will be equal to the sum of the 

 individual components; while that of the other set will be equal 

 to the excess of the currents that run from N. to S. over those 



