208 LETTERS ON NATURAL MAGIC. 



Dr. Vince, who afterwards observed this phenomenon 



under a greater variety of forms, found that the ship 



Fig. 32. 



which was here considered the real one, was only an erect 

 image of the real ship, which was at the time beneath the 

 horizon, and wholly invisible. 



In August, 1798, Dr. Yince observed a great variety of 

 these aerial images of vessels approaching the horizon. 

 Fig. 33. 



