LOW BAROMETER OF ANTARCTIC ZONE. 305 



would surround the solid earth. For our present pur- 

 poses it is sufficient to consider this supposed arrange- 



ment, as minor inequalities of the earth's surface- 

 contour have clearly nothing whatever to do with the 

 phenomenon" we are considering. . 



Let C' be the centre of the spheroid which bounds 

 the earth's fluid envelope. Then it is very clear that 

 if this envelope were of the same specific gravity as the 

 solid portion of the earth, the centre of gravity of the 

 entire mass would lie very near C', but slightly soutli 

 of that point, on account of the slight southerly dis- 



