L 103 ] 



X. On a definite arrangement, and order of the appearance and progress, of the 

 Aurora Borealls ; and on its height above the surface of the earth. In a letter 

 to Davies Gilbert, Esq. M.P. President of the Royal Society. By the 

 Rev. James Farquharson, Minister of the Parish of Alford, Aberdeenshire. 



Read January 22, and February 29, 1829. 



J^xAY I take the liberty of addressing to you, as President of the Royal So- 

 ciety, a request that you will communicate to the Society, if you shall deem 

 them worthy of its notice, the observations on the aurora borealis which I am 

 about to detail in this letter, and which have been made by me at various times 

 under very favourable circumstances, arising out of the very frequent occurrence 

 of the meteor in the latitude of my residence, about 57" 15' N. 



The immediate occasion of this communication is the interest you have ma- 

 nifested in the subject, in your observations on a luminous belt seen at Rose- 

 morran in Cornwall, 29th September last, published in the Phil. Mag. vol. iv. 

 page 453 * ; and likewise a paper by John Dalton, F.R.S., published in the Phil. 



* Mr. Gilbert's remarks referred to in the text are as follows : 



" The luminous belt which exhibited itself on the evening of September the 29th, in the present 

 year, having been noticed and described from various parts of England, I beg leave to communicate 

 its position as observed at a point very distant from most of the other stations, and therefore likely to 

 be affected by a considerable variation of parallax. 



" I was then at Rosemorran, the seat of George John, Esq., an elevated situation near Penzance, 

 twelve miles from the Land's End. My attention was called to this unusual phenomenon at about 

 eight o'clock. The belt then appeared to rise from the horizon, somewhat to the southward of west, 

 and ascended with a steady light and uniform subtense, of perhaps three degrees, towards the zenitJi, 

 passing over various stars that were scarcely altered in their appearance, till it reached Alpha Lyra, 

 then somewhat south of west, and nearly 62 or 63 degrees high. From thence diminishing in bright- 

 ness it became soon blended with the milky way, and ceased to be distinguishable. The belt seemed 

 exactly similar to a ray of the northern light, except that not the least coruscation was to be ob- 

 served. Its position could not be much out of the magnetic equator. 



" Sir William Elford, F.R.S. has favoured me with a detail of the appearances seen near Totness, 

 very much agreeing with the above statements." 



