Mr Scoresby's Description of Unequal Refraction, fyc. 293 



Art, XXVII. — A Description of some remarkable Effects of 

 unequal Refraction observed at Bridlington Quay in the 

 Summer of 1826. By the Rev. W. Scoresby, F. R. SS. 

 Lond. and Edin. M. W. S. &c. 



This interesting paper, of which we propose to give a brief ab- 

 stract, was read before the Royal Society of Edinburgh on the 

 22d of January 1827. Mr Scoresby had frequent opportuni- 

 ties of observing this class of phenomena during his voyages 

 in the Greenland seas, and in one of the latest, he saw in the 

 lower part of the atmosphere the inverted image of a ship, so 

 distinctly and beautifully defined, that he pronounced it to be 

 his father's ship, which was then about twenty-eight miles dis- 

 tant, and some leagues beyond the limit of direct vision. 



In this paper Mr Scoresby describes various phenomena of 

 unequal refraction which took place in the summer of 1826 

 about Bridlington Bay, and which he saw from his residence 

 at Bridlington Quay. These phenomena he has represented 

 in minute drawings, and therefore we must refer the reader for 

 an account of them to the original memoir, which will be speed- 

 ily published. 



On the 26th June, which was distinguished by unequal re- 

 fraction, Mr Scoresby made a sketch of the appearance of the 

 Holderness coast from the window of his sitting-room, which 

 was forty feet above the level of the sea at low water, the state 

 of the tide at the time. It then occurred to him that there 

 might be a difference of appearance at another level, and on 

 ascending to the attic story, about sixty feet above the sea, he 

 was astonished to find the phenomena altogether changed, the 

 coast now presenting almost its ordinary appearance. Upon 

 returning to his sitting-room he found the appearance exactly 

 the same as when he had first drawn it. 



He then descended to the cellar flat, about twenty feet above 

 the sea, where, on a level platform by the side of the house, 

 there was a clear view of the same coast. In this new position 

 scarcely any remains of the refractive influence were seen, al- 

 though in the middle position, viz. in the sitting-room, all the 

 phenomena of unequal refraction remained unchanged. 



The phenomena continued to preserve their character, as 



