98 Facts from the Arcana of Nature. 



no reason to assume that the higher atmospheric strata in 

 Arctic regions, remain permanently warm enough to retain in 

 suspension accumulated vapours, so as to invariably affect 

 the barometric column as noted by Antarctic explorers, during 

 their " many thousand observations." Arago presumes the 

 existence of atmospheric tides as the result of solar attraction, 

 but these not being indicated barometrically, he suggests 

 that "columns of air, though of different heights, must 

 everywhere be of the same weight, the height compensating 

 for the diminution of weight." The particles of air being 

 rendered lighter by vesicles of vapour adhering to them and 

 expanding them hollowly, certainly ascend, but although thus 

 lightened in the denser strata near the Earth's surface, the 

 increased height of the column must cause an equilibrium of 

 weight as before. But if elevation of the ocean level dis- 

 places the densest portion of the atmosphere, deficiency of 

 weight will manifest. itself by diminution of pressure. 



Observations in nature demonstrate that the waters en- 

 veloping the globe, are steadily retreating from certain shores, 

 and gaining upon others ; and this on the grand scale of our 

 whole world, without reference to local changes, the possible 

 result of igneous agencies ; or of sea waves, in silting up, or 

 denudation. At same time, astronomical observation discloses 

 the fact of the continuous approximation of the plane of the 

 heretofore supposed permanent equatorial intersection of the 

 globe, to the plane of the Earth's orbit of revolution. Are 

 we not therefore justified in the belief that a natural process 

 is at work slowly increasing the density of the matter of the 

 northern hemisphere, and thus its tendency towards a 

 position of coincidence of the planes of the equator and 

 ecliptic ; evincing an alteration — progressing uninterruptedly 

 in one direction — in the Earth's centre of gravity. This, 

 however small, and imperceptible in annually recurring 

 quantity, must inevitably effect, as well as mark, a change in 

 the axis of rotation, and consequently, in the position of the 

 polar extremities upon the sphere, giving rise to alteration of 

 the relative positions of the zones of temperature ; so that, 

 while one area is being absorbed within the Arctic circle, 

 another within the same latitude, as presently defined, is 

 progressing at the same rate of motion, towards the temperate 

 zone. 



It is obvious that the movable matter or oceanic envelope 

 of the globe, must, in obeying the natural law of gravitation, 

 converge towards the centre of gravity of the whole volume 



