3i8 



PHYSIOGRAPHY. 



[CHAP. 



But without having recourse to a voyage of circumnaviga- 

 tion, very simple reasons afford proof that the surface of the 

 earth is curved, not only in one direction but in all directions ; 

 or, in other words, that it has the shape of a ball. 



One of the most commonly cited, but at the same time 

 one of the most convincing proofs of this rotundity, is based 



Fig. gS. — Disappearance of a ship at sea. 



upon a simple observation which any one can make for him- 

 self at the sea-side. If a ship be watched, as she leaves 

 port, it will of course be seen that she gets smaller in size 

 and fainter in outline the farther she stands out to sea. But, 

 in addition to this change of size and of distinctness, the 

 figure of the ship suffers a change. In fact, the hull of the 

 vessel seems gradually to sink into the sea, and at length dis- 

 appears altogether. Yet it might fairly be supposed that the 

 hull, being the largest part, would remain longest in view. 



