horiz.ontaJ RefraSllon of the Air. 6l 



than I ever obferved it at any other tune; particularly to- 

 wards the eaftj on which part alfo the unufual refraftion was 

 the ftrongeft. 



During the remainder of my ftay at Ramfgate, which was 

 about five weeks, I continued daily to examine all the fliips 

 in fight ; but I difcovered no phasnomena fimilar to thofe 

 which I have here given a defcription of. The phaenomenon 

 of the {hip obferved by Mr. Huddart, differed altogether 

 from thofe above defcribed, as the inverted image which he 

 obferved was below the (liip itfelf. An appearance of this 

 kind I obferved on Auguft the 17th, about half an hour after 

 three o'clock in the afternoon, of which Fig. 9. is a repre- 

 fentation. The real fliip is reprefented by A, and the image 

 byB; er, mv, the hulks; st the flag, and iv x its image, 

 juft touching it, with the fea xy below. Between the two 

 hulks fome faint dark fpots and lines appeared, but I could 

 not difcover what they were the reprefentatives of. The 

 vcfl'el, at the time of this appearance, was not quite come up 

 to the horizon ; and, as it approached it, the image gradu- 

 ally diminifhed, and totally difappeared when the fiiip ar- 

 rived at the horizon. 



It remains now, that we inquire into the caufes which 

 might produce the very extraordinary eft'etls which have 

 been above related. From the phasnomena, we are imrae-- 

 diately led to the nature of the path of the rays of light to 

 produce them ; and we may conceive, that the air may pof- 

 fibly be in fuch a fl:ate as will account for the unufual traft 

 which they muft have defcribed. For, let bz (Fig. 10.) be 

 the furface of the fea ; ab an object ; E the place of the eye ; 

 -a r E, bsY., the progrefs of two rays, by the ufual refraftion, 

 from the extreme parts of the objet^ to the eye ; to thefe 

 curves draw the tangents E^', E^', and a' ^' will be the 

 image of the objeft, as ufually formed. Now, if we take the 

 cafe reprefented in Fig. 4, let a" b" reprefent the inverted 

 image, and a'" b'" the ere£l image ; join a" E, a'" E, and 

 h" E, ^''E, and thefe lines muft refpedively ^c, the direc- 

 tions of the rays entering the eye from a and b, in order to 

 produce the images a" b'^ and a'^' b"; hence, thefe lines 

 uiuft be tangents at E, to the curves which are defcribed by 



the 



