TRANSACTIONS OF THE SECTIONS. 25 



of greater or less brilliancy, occurring at stated intervals ; 2nd, an expanding and 

 contracting of the whole body of light, not only vertically, but also laterally ; and 

 3rd, a motion amongst the stars. 



1st. Pulsations were noticed 1850, March 6d. 7h. 42m., of greater and less bril- 

 liancy in periods of 30s.; in these alternations it invariably receded to a certain dimness, 

 and then brightened again to a fixed extent. The pulsations were again noticed on 

 March 7th, 9th, 10th, 11th; 1851, January 27th, March 20th (when^'they were very 

 marked), and 22nd. These pulsations were again 30s., alternating from change to 

 change, as they were last year. 



2nd. The vertical expansion and contraction of the body of light on 1850, March 

 6d.at7h.42m., were4°30'. The longitude of apex, when most brilliant, was 8 21° 30', 

 receding to longitude of apex e 17° when least bright. InlSSl, March 20d. 8h., this 

 expansion and contraction were 3° ; the max. long, of apex being 51°, min. long, of 

 apex 48°, the mean long, of apex being 49° 30'. 



At three different periods the lateral body of light also widened, and this occurred 

 each time when at its maximum degree of brilliancy. This was first noticed at 

 7h. 55m., when the north edge extended to (3 Arietis, again at 7h. 59m., when it 

 extended midway between ^ and a Arietis, and thirdly at 8h. 3m , when it 

 covered a Arietis. It remained in this widened state from Is. to 3s., returning each 

 time to its mean place between /3 and y Arietis; once when very dim the north edge 

 was thought to have receded to y Arietis (viz. at 7h. 50m.). The southern edge un- 

 fortunately had not such good guide stars for measuring, so that I cannot speak 

 positively as to whether it receded when the north edge advanced, yet the impression 

 made at the time was that it did not, and at 7h. 59m. appeared to widen with the 

 north edge. 



3rd. Its path amongst the stars. 



1850. February 13d. 7h. 30m., Saturn was 2° within its S. edge. Its apex had an 

 altitude equal to that of the Pleiades. 



1850. March 6d. 7h. 42m. S. edge confused, appeared to pass through | Ceti; 

 et Ceti was 2° within the edge. The N. edge, tolerably bold, passed through g 

 Piscium, midway between y and /3 Arietis, and 1° S. of S Arietis, 



1850. March 7d. 8h. Om. N. edge extended to /3 Arietis. 



1850. March lOd. 7h. 50m. ' N. edge extended to a. Arietis. 



1850. March lid. 7h. 59ra. N. edge half-way between ct and /3 Arietis, S. edge 

 just N, of |W Ceti. | Ceti about 2° within the edge. 



1850. March 12d, 8h, Om. N. edge between « and /3 Arietis, shghtly nearer /3 

 than OS. 



1850, March 13d. 8h. Om, N. edge between ct and /3 Arietis, yet still nearer fi. 



1851. January 27d. 7h. Om. N. edge passed near a Pegasi. 



1851. March 20d. 8h. Om. N. edge passed midway between /3 and y Arietis, the 

 S. edge cut fi Ceti. 



The following are the approximate positions of the northern edge at a mean alti- 

 tude equal to x, fi, and y Arietis : — 



Epoch. M. N. decl. 



1850. March 6d 1° 46^' ,... 18° 40'. Motion direct. 



— — 7d 1 4ei .,,. 20 5 



— — lOd 1 59 ,...22 45i- 



— — lid 1 52i 21 25-J. Motion retrograde, 



— — 12d 1 51 .,.. 21 10 



— — 13d 1 49 .... 20 50 



1851. March 20d 1 46i .... 18 40 



Extra Remarks. 



Epoch 1850. February 13d. 7h. 30m. Exceedingly brilliant, being brighter than 

 the galaxy about the Swan. Saturn was thought to be dimmed by it. 



Epoch 1850. March 6d. 7h. 42m, Extent of base on horizon 36°; its S. edge cut 

 the horizon 13°S, of W., and its N. edge 23°N.of W.; axisslightly N, of Pleiades, and 

 horizon 5° N. of W. The S. edge somewhat confused. The alternations in bright- 

 ness were first noticed by several small stars being alternately visible and invisible; 



