26 Mr. Riddle on the Occultation of $ Scorpii. 



portunity, more especially as we contemplate investigating the 

 latter subject on much more general principles than we have 

 employed in that of which we nave been treating. 



, John Herapath. 



Errata in the preceding part of this paper, printed in the last Number of 

 the Philosophical Magazine and Annals. 



Page 424, last line, for R*_ 2 read R t _ 2 



425, in (16) for r + R t + R 2 read r + R + R, + R 2 



425,in(18)for e xrn " 1 read e* r n-l 



V. On the Occultation of ft Scorpii, September 25, 1827. By 

 E. Riddle, Esq. 



To the Editors of the Philosophical Magazine and Annals. 

 Gentlemen, 

 r T , HE double star |9 Scorpii has been occulted almost every 

 ■*• lunation during the present year ; but only the occupa- 

 tions in May, July, and September, occurred at such times as 

 admitted of their being seen in this country. I happened to 

 see that which took place on September 25th, at about six 

 o'clock in the evening; and as it was not seen by any other 

 person that I have met with, and was attended by some cir- 

 cumstances which I believe were unexpected, it seems desire- 

 able to ascertain, if possible, whether it was witnessed by any 

 one else in this neighbourhood, and to what extent the phe- 

 nomena differed from those which I observed. 



Perhaps the insertion of this notice in the Philosophical Ma- 

 gazine may elicit a communication on the subject from some 

 gentleman who observed it with means superior to mine, as I 

 had merely a 30-inch achromatic, with a power of about 80. 



The stars are about 14" apart, the smaller one the more 

 northerly; and though the elements of the occultations of both 

 stars are given in the Nautical Almanac, and both marked 

 there as visible at Greenwich, where I observed, which was in 

 lat. 51° 28' 53" N., long. 8" W., and about 120 feet below the 

 level of the axis of the transit instrument, at the Royal Obser- 

 vatory, the larger star was not occulted at all. When I first 

 turned the telescope on the moon, I saw both the stars very 

 distinctly, a little to the eastward of the southern enlightened 

 horn. The smaller one vanished behind the dark limb, a lit- 

 tle before it reached the horn. I expected every instant as the 

 laro-er one approached the enlightened edge, that it would be 

 occulted by some of the luminous protuberances near the horn; 

 but it glided steadily along, appearing in my telescope, nearly 

 if not quite in contact with the enlightened limb. It never 



was 



