HISTORY OF PHYSICAL ASTRONOMY.

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previous to the dissolution of the annulus. At first several dark linesdart forward from the moon’s limb, and unite themselves to that of thesun; then they suddenly contract so as to assume the appearance of beads,and immediately afterwards the annulus is dissolved. On the occasion ofthe annular eclipse of May 15, 1836, this phenomenon was especiallyobserved in Scotland by Mr. Baily, who has given a lively description ofit in a paper on the eclipse which appears in the tenth volume of theMemoirs of the Astronomical Society. It may not be uninteresting,however, to show that an appearance more or less analogous to it has beenwitnessed on several previous occasions, both of total and annular eclipses.

Halley mentions, in his account of the total eclipse of 1715, that abouttwo minutes before the total immersion the sun was reduced to a veryslender crescent of light, the extremities of which seemed to lose theiracuteness and to become round like stars *.

During the total eclipse of 1724, Delisle remarked that the part of themoon’s limb, where the total immersion was about to take place, appearedto him irregular and indented f.

But, as has been already mentioned, it is during annular eclipses of thesun, that the phenomenon witnessed by Mr. Baily is more especiallyconspicuous.

In his account of the annular eclipse of 1737, Maclaurin cites a letteraddressed by Professor Bayne to Lord Aberdour, containing the followingstatement:—“What appeared to me most entertaining, considered as anobject of sight, was when the extremities of the horns, formed upon theface of the sun, seemed as if they had been in the action of uniting theirpoints; the inequalities on the extremity of the moon’s disk gave theappearance as it were of small bodies in particular motion (.

In Short’s paper on the annular eclipse of 1748, which has been alreadyreferred to, there appears a statement from the Rev. Mr. Irvine , whoobserved the eclipse at Elgin, in which he asserts that, previous to thejoining of the cusps of the sun, as also at the breaking up of the annulus, heperceived a quick tremulous motion and several irregular bright spots betweenthe cusps, which disappeared in a few moments. He adds that loth theformation and breaking (of the annulus) were very sensibly to be observedand parted in a moment; affording a very pleasant sight, by the irregulartremulous spots of the sun§.

The following description of the phenomenon as witnessed in America by Mr. S. Webber, during the annular eclipse of April 3, 1791, is moreprecise than any that has been hitherto cited:—“ At both the internalcontacts there was a curious and striking appearance of what may becalled drops, on account of their resemblance to drops of a fluid. At thefirst contact, when the horns of the sun were forming a ring about themoon, these luminous drops suddenly appeared, at several different points,with very little difference of time. At first they were nearly circular;but they rapidly extended themselves along the limb of. the sun, till,uniting, they completed the annulus. At the second contact severalbreaches in the annulus almost instantaneously succeeded the first, atdifferent distances from each other; and the oblong drops includedbetween them contracted and vanished.”||

A similar phenomenon was witnessed by Nicolai at Manheim, during

* Phil. Trans., 1715, p. 248. f Mem. Acad, des Sciences, 1724, p. 317.

I Phil. Trans., 1737, p. 182. § Ibid., 1748, p. 594.

|| Mem. Amer. Acad, of Arts and Sciences, vol. ii., part i., p. 20.