1-6 
Mr. Vince's Observations upon 
ascended ; but, as the ship did not sink below the horizon, I 
had not an opportunity of observing at what time, and in what 
order, the images would have vanished, if the ship had so dis- 
appeared. 
Being desirous of seeing whether the same effect was pro- 
duced upon the other ships which were visible, I directed my 
telescope to another ship A, (fig. 2.) whose hulk was just in 
the horizon xy ; when I observed a complete inverted image 
B, the main-mast of which just touched that of the ship itself. 
In this case, there was no second image as before. The ship A 
moving upon the horizon, B continued to move with it, without 
any variation in its appearance. 
The next ship which I directed my telescope to, was so far on 
the other side of the horizon x y, as just to prevent its hulk from 
being seen, as is represented by A, (fig. 3.). And here I ob- 
served only an inverted image of part of the ship; the image y 
of the topsail, with the mast joining that of the ship, the image 
x of the top a of the other mast, and the image z of the end c 
of the bowsprit, only appearing at that time. These images 
would suddenly appear and disappear very quickly after each 
other; first appearing below, and running up very rapidly, 
showing more and less of the masts at different times, as they 
broke out ; resembling, in the swiftness of their breaking out, 
the shooting out of a beam of the Aurora borealis. As the ship 
was descending on the other side of the horizon, I continued my 
observations upon it, in order to discover what changes might 
take place ; when I found, that as it continued to descend, more 
of the image gradually appeared, till at last the image of the 
whole ship was completed, with their main-masts touching 
each other; and, upon the ship descending lower, the image 
