138 



THE OCEAN. 



Lawrence. Sometimes another image may be seen 

 above the inverted one, and sometimes, but very rarely, 

 ev f n a fourth. In such cases, the third is always 

 in a right position, and the fourth inverted like 



Distortions of Irregular Refraction. 



the second. An image of a vessel is sometimes seen 

 projected upon the sky, when nothing corresponding 

 to it is visible below, the real object being far below 

 the horizon. Mr. Scoresby thus saw his father's 

 ship, the Fame, drawn upon the sky, and by the aid 

 of a telescope could make her out so distinctly as to 

 pronounce with confidence upon her identity, when, 

 by comparing notes afterwards, it was found that she 

 was thirty miles distant at the time, and seventeen 

 miles from the extreme point of vision. Somewhat 

 allied to this is the bright gleam seen by night above 

 field-ice, called ice-blink, which is often very service- 



