346 The Low Barometer of the Antarctic Temperate Zone. 



a slight displacement southwards of the earth's centre of 

 gravity. If, then, C is the centre of the black circle in Fig. 3, 

 representing the solid part of the earth, the centre of gravity 

 of this part lies (in the Fig.) slightly below C — between C and 

 C, let us suppose. 



Now we see that, owing to this slight displacement, the' 

 watery envelope of the earth tends southward. If the earth 

 were a perfectly uniform spheroid, it is clear that there would 

 be a tendency to some such arrangement as is represented (on 

 a greatly exaggerated scale) in Fig. 3, in which the shaded 

 part represents the sea — that is, a shell of water, thicker 

 towards the south, would surround the solid earth. For our 

 present purpose it is sufficient to consider this supposed ar- 

 rangement, as minor inequalities of the earth's surface- contour 



pji 



have clearly nothing whatever to do with the phenomenon we 



are considering. 



Let C bo the centre of the spheroid which bounds the 

 earth's fluid envelope. Then it is very clear that if this en- 

 velope were of the same specific gravity as the solid portion 

 of the earth, the centre of gravity of the entire mass would 

 He very near C, but slightly south ot that point, on account of 

 the slight southerly displacement of the centre of gravity of 

 the solid portion. But when we consider that the specific 



