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HISTORY OF PHYSICAL ASTRONOMY.

The late Mr. Henderson, who observed the annular eclipse of May 15,1836, at Edinburgh , states, in an account of his observations of thephenomenon, that, previous to the formation of the annulus, when thecusps were about 30° or 40° from each other, an arc of faint reddishlight was seen extending between them. This appearance lasted severalseconds *.

The observations made in the United States of America during theannular eclipse of February 10, 1838, furnish additional illustrations ofthe same phenomenon. Prof. Henry, who observed the eclipse atPrinceton College, New Jersey , states that about two minutes before theformation of the ring, he perceived an arch of faint light between thecusps, and shortly afterwards a brush of greater intensity, projecting fromnear the lower cusps f. A similar appearance was witnessed by Prof.Johnson, who observed the eclipse at Philadelphia . About a minutebefore the formation of the ring, he perceived an arch of faint lightbeyond the cusps, with a speck or brush in the centre extending outwardsto a distance of two degrees. At the instant of the formation of theannulus, the arch of light had much increased in brightness. Thebrush which was originally in the centre, now extended from cusp to cusp,radiating outwards to the extent of nearly three digits j.

Two observations at least, tending to illustrate the subject under con-sideration, were made during the annular eclipse of October 9, 1847.

. Dr.' Forster, who witnessed the eclipse at Bruges , has stated in an accountof his observations that there was visible a very remarkable luminous arc orridge of light, differently coloured from the rest of the sun, extending alongand immediately on the limb of the moon between the cusps. The appear-ance lasted nearly five minutes §. Captain Jacob, who observed the eclipseat Bombay, states, that shortly before the annular phase, a faint ray orbrush of light was seen issuing from the sun’s northern cusp, W'hich soonafter extended in both directions as a tangent to the sun's limb ||.

It might be expected, that the arcs and specks of light observed aroundthe moon’s dark limb during the total and annular eclipses of the sun,might be also occasionally seen during partial eclipses of considerablemagnitude. The following are a few instances in which phenomena ofthis nature appear to have been visible.

It has been already mentioned that an eclipse of the sun happened inthe year 1605, which was total at Naples. Kepler states that at Antwerp ,where the upper limb of the sun projected about a digit beyond themoon’s limb, the circumference of the lower limb of the moon vvas ren-dered visible by means of a ruddy light bordering it II.

On the 22nd of June, 1066, there occurred a partial eclipse of the sunwhich was visible at London . In an account of the phenomenon as observedby Hooke and several other individuals, it is stated that “ about the middlebetween the perpendicular and westward horizontal radius of the sun,viewing it through Bayle’s 60-feet telescope, there was seen a little of thelimb of the moon without the disk of the sun, which seemed to some of

* Mem. Ast. Soc,,vol. x., p. 37.

+ Silliman’s Journal, vol. xxxviii., p. 166. I Ibid., vol. xxxviii., p. 159.

§ This statement is contained in a letter to Prof. Powell (Brit. Ass. Rep., 1848;Transactions of the Sections, p. 4).

H Monthly Proc. Ast. Soe., vol. viii., p. 27. De Stella Nova, p. 116.