282 TERRESTRIAL REFRACTION AND MIRAGE. 
(Fig. 12) almost out of sight with its mainmast appearing above the 
Fig. 12. 
MUN 
PANT 
horizon. Above in the sky he saw first of all an inverted image of the 
complete ship; and then an image of some sea, and above that an 
erect image of the ship. As the ship sailed along these images sailed 
along with it, and as the ship gradually got further and further off, the 
mainmast gradually sank still more, and as it sank the images rose ; 
but, as he writes, the ship did not disappear absolutely from sight, and 
he did not observe in what manner the images finally disappeared. 
These effects were observed through a telescope magnifying about 80 
or 40 times, so that they could not have been observable by the unaided 
eye. Then again he saw a ship on the horizon with an inverted spectre 
of a ship above it, with the mainmasts joined in the manner shewn in 
Fig. 13. 
TG ye gs 
Win 
i 
I 
SOrEE 
In Fig. 14 the real ship seems to have been completely out of 
sight, and he saw the inverted ship with a portion of the image, as it 
were, below the horizon; the top of the mainmast was not visible; and 
then above this an erect image of the ship. This is one of the most 
