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Extraordinary Case of Atmospheric Redaction. By John 

 Cruickshank, Esq. Professor of Mathematics in the Maris- 

 chal College, Aberdeen. Communicated by the Author. 



Mahischai. College, Aberdeen, 

 Sir, \bth August \&ifi. 



Having been informed lately by my friend, the Rev. Dr For- 

 bes of King's College, that you were desirous of collecting facts 

 respecting extraordinary cases of terrestrial refraction, I send 

 you the subjoined account of phenomena which I observed here 

 on the 10th June 1826. I am, &c. 



John Cruickshank. 

 To Professor Jameson, &c. &c. 



On the morning of the 10th June 1826, there was a thick 

 fog at Aberdeen, with a slight breeze of wind about south-east 

 by east. Between eight and nine a. m. the fog vanished from 

 the land, and bright sunshine succeeded, which continued till 

 late in the afternoon ; but fogs, apparently dense, remained at 

 a distance on the sea, and occasionally extended to the shore at 

 some points till after mid-day. From the observatory of Ma- 

 rischal College at noon, the rocks about Slains Castle, on the 

 Buchan coast, and distant about twenty-four miles, attracted 

 my attention, by appearing more elevated, and with much greater 

 distinctness of parts, than usual. Places beyond Slains Castle, 

 which are not visible from Aberdeen in ordinary states of the 

 atmosphere, were at some instants distinctly seen. The rocks, 

 and the adjacent land, to the distance of about two miles, west 

 of them, seemed to vary in altitude almost every ten seconds, 

 the whole tract appearing alternately to rise gradually to three 

 or four times its ordinary apparent height above the level of 

 the sea, and subside again into itself. Thus far the phenomena 

 were observed with the naked eye, and during the space of 

 about five minutes. But, upon examining the same tract of 

 country with a tel< scope, a three and a half feet achromatic with 

 a low power, I found the appearances presented by smaller ob- 

 jects to be still more interesting, particularly those objects which 



