280 
TERRESTRIAL REFRACTION AND MIRAGE 
are shewn in Fig, 9, which must cause very extraordinary dis- 
Fig. 9, 
tributions of air density, and give rise to quite remarkable 
vertical and lateral refractions. 
(3) Unequal and changeable density of the air, which of course 
bution of ice; and 
results in the main from the extraordinary irregular distri- 
refracted objects are seen. 
(4) In the case of multiple images, alternations of parallel 
strata of different densities in the medium through which the 
The diagram (Fig. 10) I have copied from Commander Scoresby’s 
Fie. 10. 
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book on the subjecteehis book on West Greenland. The appearances 
