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HISTOEY OF PHYSICAL ASTKONOYIY.

the annular eclipse of September 7, 1820. In his account of the eclipse,he states that about a second before the annulus was formed, the finecurve of the moon’s disk, then immediately in contact with the edge ofthe sun, appeared broken into several parts; and in a moment these partsflowed together like drops of water or quicksilver near each other. At thedissolution of the annulus, a similar appearance presented itself; for thedelicate thread of light then formed by the annulus, instead of beingbroken into one place only, was in an instant divided into several placesat once.”*

The phenomenon was also observed on the occasion of the same eclipseat Bologna, by Be Zach, who has given the following interesting descrip-tion of it:—“ The most beautiful spectacle was the end of the annulareclipse or the instant of the formation of the annulus. The mountainsof the moon appeared very distinct. Her limb seemed to be indented,and when it was upon the point of touching the sun’s limb, it appeared like acomb or a saw biting the edge of the solar disk. Before the contact of thetwo limbs was effected, there was visible, not a continuous thread of light,but a number of luminous points, resembling a row of so many pearlbeads, separated by dark intervals. This beautiful phenomenon lastedonly an instant; for the contact of the limbs, and the total disappearanceof the last trace of light, was instantaneous.”!

The same appearance was also witnessed at Amsterdam by several ob-servers of the eclipse, accompanied in some instances with new features, butthe description given by Mr. Baily, of the phenomenon as it presented itselfto him on the occasion of the annular eclipse of May 15, 1836, embodies allthe particulars by which it has been hitherto distinguished. He states thatwhen the cusps of the sun were about 40° asunder, a row of lucid points,like a string of bright beads, irregular in size and distance from eachother, suddenly formed round that part of the circumference of the moonthat was about to enter on the sun’s disk. Its formation was so rapid thatit presented the appearance of having been caused by the ignition of afine train of gunpowder. Mr. Baily was under the impression that thisphenomenon indicated the correct formation of the annulus, and he wasaccordingly about to note the time of its occurrence. “ My surprise,however, was great,” says he, “ on finding that these luminous points, aswell as the dark intervening spaces, increased in magnitude, some of thecontiguous ones appearing to run into each other, like drops of water; forthe rapidity of the change was so great, and the singularity of the appear-ance so fascinating and attractive, that the mind was for the momentdistracted and lost in the contemplation of the scene, so as to be unable toattend to every minute occurrence. Finally, as the moon pursued hercourse, these dark intervening spaces (which at their origin had theappearance of lunar mountains in high relief, and which still continuedattached to the sun’s border) were stretched out into long, black, thick,parallel lines, joining the limbs of the sun and moon; when all at oncethey suddenly gave way, and left the circumference of the sun and moonin those points, as in the rest, comparatively smooth and circular; and themoon perceptibly advanced on the face of the sun.” In fact the phe-nomenon could not be more accurately imagined than by supposing, for

* Mem. Ast. Soc., vol. i., p. 142.

f Correspondance Astronomique, vol. iv., p. 171; Smyth’s “Cycle of CelestiaObjects,” vol. i., Appendix .