440 PHILOSOPHICAL TRANSACTIONS. [ANNO 17QQ. 



I have here described all the different phenomena which I observed from the un- 

 usual refraction, of most of which I saw a great many instances. Every ship which 

 I observed on the other side of the horizon of the sea, exhibited phenomena of 

 the kind here described, but not in the same degree. Of 2 ships which in dif- 

 ferent parts, were equally sunk below the horizon, the inverted image of one would 

 but just begin to appear, while that of the other would represent nearly the whole 

 of the ship. But this 1 observed in general, that as the ship gradually descended 

 below the horizon, more of the image gradually appeared, and it ascended ; and 

 the contrary when the ships were ascending. On the horizon, in different parts, 

 one ship would have a complete inverted image; another would have only a partial 

 image; and a 3d would have no image at all. The images were in general ex- 

 tremely well defined ; and frequently appeared as clear and sharp as the ships them- 

 selves, and of the same magnitude. Of the ships on this side of the horizon, no 

 phenomena of this kind appeared. There was no fog on our coast; and the ships 

 in the Downs, and the South Foreland, exhibited no uncommon appearances. 

 The usual refraction at the same time was uncommonly great ; for the tide was 

 high, and at the very edge of the water I could see the cliffs at Calais a very consi- 

 derable height above the horizon ; whereas they are frequently not to be seen in 

 clear weather from the high lands about the place. The French coast also appeared 

 both ways, to a much greater distance than I ever observed it at any other time; 

 particularly towards the east, on which part also the unusual refraction was the 

 strongest. 



During the remainder of my stay at Ramsgate, which was about 5 weeks, I con- 

 tinued daily to examine all the ships in sight; but I discovered no phenomena 

 similar to those above described. The phenomenon of the ship observed by Mr. 

 Huddart, differed altogether from those above described, as the inverted image 

 which he observed was below the ship itself. An appearance of this kind I ob- 

 served on August the 17th, about half an hour after 3 in the afternoon, of which 

 fig. 9 is a representation. The real ship is represented by a, and the image by b; 

 er, mv, the hulls; st the flag, and wx its image, just touching it, with the sea xy 

 below. Between the 2 hulls, some faint dark spots and lines appeared, but I could 

 not discover what they were the representatives of. The vessel, at the time of this 

 appearance, was not quite come up to the horizon ; and as it approached it, the 

 image gradually diminished, and totally disappeared when the ship arrived at the 

 horizon. 



It remains now, that we inquire into the causes which might produce the very 

 extraordinary effects above related. From the phenomena, we are immediately led 

 to the nature of the path of the rays of light to produce them ; and we may con- 

 ceive, that the air may possibly be in such a state as will account for the unusual 

 track which they must have described, For, let bz, fig. 10, be the surface of the 

 sea ; ab an object ; e the place of the eye ; arE, bsE, the progress of 2 rays, by the 

 usual refraction, from the extreme parts of the object to the eye ; to these curves 



