Royal Astro?iomical Society. 145 



clear, tliis small spot only excepted ; the moon's limb was also per- 

 fectly well-defined except in this point. The ligament lasted for 3* 

 or 4', perhaps more, elongating as the moon advanced, and was at 

 length suddenly retracted into her circumference, the end appearing 

 broken or toothed. At the breaking of the annulus the phsenomenon 

 was different ; the moon's limb continued to approach that of the 

 sun, till, when very close, a portion of the former, about 30° in ex- 

 tent, suddenly flowed over in dark lines, with bright spaces between, 

 which almost immediately vanished, the whole appearance not last- 

 ing above 2'. The first appearance was like that shown in jjlate 1, 

 fig. 10 of the Society's Memoirs, vol. x., and the last more resembled 

 figs. 1 and 3 of the same plate, but the lines were more numerous 

 though they could not be counted. The telescope used was a 3^ 

 foot by Dollond, with a power of 40. 



" Not being in good health, I was unable to make any further 

 observations of importance, except that the temperature of the air 

 fell during the eclipse from 87° to 84°'5, and rose again to 85°-5 at 

 the termination; and that, while the annulus lasted, the sun's rays 

 had scarcely a perceptible effect on the thermometer. 



" The time of the retraction of the ligament was noted as that of 

 the formation of the annulus ; and the time when the lines began to 

 run across as the time of the end of the same. No light could be 

 seen round the moon's limb when off the sun, either before or after 

 the annulus." 



Beads in Annular Eclipses. By the Rev. Professor Baden Powell. 



The author considers the fact of the existence of the phaenomenon 

 in question as sufficiently well-established, notwithstanding the 

 equally admitted discrepancies in the accounts given of the appear- 

 ance of the beads by different observers. Observers differ as to such 

 points as the stationary or fluctuating character of the beads and the 

 degree of their changes into threads ; and they have sometimes been 

 seen by one observer and not by another when the circumstances 

 have been in some degree different. These discrepancies the author 

 thinks due in some cases to the different coloured glasses employed, 

 and in others to the loss of light, as, for example, when the images 

 are projected on a screen. He thinks Mr. Caldecott's explanation 

 of tlie tremulousness of the beads (as being due to atmospheric mi- 

 rage) unsatisfactory, and is rather inclined with Mr. Airy to attribute 

 it, in part, to the rapid decrease of the intensity of the sun's liglit 

 near the borders. 



'I'lie author considers the whole of the phaenomena that have been 

 observed to be due to two causes, viz. to the rapid decrease of light 

 at the sun's edge, and to the acknowledged law of irradiation, that 

 it increases with the increase of the intensity of the light. 



'I'his being allowed, he imagines that " any small opening or notch 

 on the moon's edge will give rise to an enlarged image or patch of 

 liglit by irradiaticm ; and that this will be much greater as the part 

 occnsioning it is further advanced on the sun's disc ;" thus the for- 

 mation of beads is accounted for, and their elongation. 



" Again, when the junction is broken, the same causes will account 

 Phil. Mag. S. S. Vol. 32. No. 213. Feb. 1848. L 



