ASTRONOMY. 



[PHENOMENA OF SOLAR KCL1 



and before the want of an atmosphere to oar satellite was 

 established by numerous proof*, it was the most natural 



one which could be imagined ; although the great breadth 

 of the rinu' would go to prove that its height must be 

 three or four hundred miles, or ten times the extent of 

 the earth's atmosphere. No such difficulties exist in the 

 case of its being supposed to be the solar atmosphere, 

 while its concentric form, in regard to the sun at the 

 different periods of observation, tends still further to con- 

 firm this conjecture. By what has already been stated 

 of the photosphere of the sun, and the different strata 

 which surround its surface, as well as the appearance of the 

 zodiacal light, this may be deemed to be, in every respect, 

 the most probable co'njecture.* The corona, however, 

 cannot be identified as forming the zodiacal light, for it 

 has mostly been observed of a circular form, whilst the 

 latter is elliptical ; even where the corona has been 

 noticed to be protuberant on opposite sides, the greater 

 axis does not take the direction of the ecliptic. 



Red Flame*. In the eclipses of 1715 and 1733, when 

 the sun was wholly eclipsed, and only the corona was 

 visible, the margins of the moon were noticed to be 

 marked with some red spots, which remained visible for 

 some seconds. Whilst observing the corona in the eclipse 

 of 1842, these appearances again became unexpectedly 

 conspicuous to the different observers. They were first 

 observed a few seconds after the time of total obscuration, 

 and were of a fine crimson tint being compared by one 

 observer to the peaks of the Alps illumined by the setting 

 sun ; and, by another, to beautiful sheaves of flames, 

 which remained visible even after the sun had emerged. 

 The length of the most considerable was, by actual 

 measurement, found to bo equal to 1J minutes of arc. 

 Only two or three isolated prominences were perceived 

 '10 observers stationed in the south of France ; but to 

 MM. Strove and Schidlowsky, these rose-coloured flames 

 burst out at several parts of the lunar disc a very large 

 inn of the periphery being garnished with this red- 

 dish bordering. M. Littrow noticed that they changed 

 lour as the eclipse advanced, being at first white, 

 then ro*e colour, and finally violet, passing afterwards in 

 a reverse order through the same tints. In the eclipse of 

 liese crimson projections were beautifully seen, 

 and by some observers in great number. Some seen 

 were, in this instance, crooked, and resembled a flame 

 bent aside by the wind, but their colour was of the same 

 rrmaikable tint as in the former case. In the eclipse of 

 1706. observed by Captain Stannyann, at I '.me, "a 

 blood-red streak of light" was noticed ; and llalley, in 

 171"', saw a similar "Jong, and very narrow streak, of n 

 dusky but strong red light " Equally with the corona, 

 the*e appearance* have been conjectured to be in the at- 

 BMphere of the tun, and to be in no way connected with 

 Bre ant,, p. M9. 



the moon. Their rcddUh light would *eem to show that 

 they were of a cloudy nature, resembling our tei 

 clouds, and absorbing all the rays of the spectrum, with 

 the exception of the red. (See, also, page 105, <mfc). 



Baily'f Bead*. In some case* when the margin of the 

 moon comes in contact with that of the sun, instead of the 

 faint and regular thread of light which would be sup- 

 posed to ensue under those circumstances, the appearance 

 presented is a broken glimmer of light, which was first 

 notice.! by the late Mr. Baily, who compared it to beads 

 of light. These are noticed in total as well as annular 

 eclipses, and were seen by different observers in tlio 

 eclipse of 1851. They are generally regarded as be in.; 

 due to the rough and mountainous edges of the n 

 coming in contact with the margin of the sun, and the 

 light proceeding from the latter sluningthrough the rJiiiita 

 or valleys of the moon, the effect being greatly increased 

 by irradiation. 



Method of Obtervatian. We can follow the different 

 phases of a solar eclipse without the help of a telescope, 

 and by merely making use of a piece of coloured glass; 

 that colour which is technically termed by opticians 

 London Smoke being the most convenient for this pur- 

 pose. If a pin-hole be made in a piece of card, and tho 

 image received on a screen, the disc of the sun, and tho 

 various phases it assumes from the interposition of tho 

 moon, likewise become very apparent, and we have thus a 

 still more simple method of following the phases of an 

 eclipse. The form of the aperture, or the pin-hole, is of 

 little consequence in this instance, provided it be small. 

 Application of Photoynijilnj. For particulars on this 

 subject, the reader may refer to the article on (VKsti.il 

 Photography, in the section on Light (page 104). 



Occupations of Stars by the Moon. The occultations of 

 stars by tho moon are analogous to eclipses of the sun, 

 and their graphical projection may be made with some 

 slight modifications as in that case, and the same 

 formulae may be applied to their prediction. All tho 

 planets may be occulted by the moon, but only such of 

 the fixed stars as are situated near the eclipi 

 within the limits of the moon's latitude. Among the 

 brighter stars which can suffer eclipse those of I: 

 Spica, Aldebaran, An tares, and the group of the l'lei;ules, 

 may be mentioned. An occultatiou can be scon at many 

 different parts of the earth's surface, and their : 

 observation forms one of the best means of determining 

 the longitude, being much more exact than the occulta- 

 tions of Jupiter's satellites, as tho moments of iniiuci 

 aud emersion are instantaneous. The portion of the 

 earth's surface at which the star appears to be occulted at 

 the same instant, will have a diameter equal to that of tho 

 moon, nd will pass, like the shadow of the moon, over a 

 certain zone of the earth. As the star has no perceptible 

 diameter, there can be no penumbra in such a case, even 

 if tho light of the star were sufficient to cast a shadow. 

 This circumstance renders tho calculation more limpla, 

 which likewise follow* from the star having neither 

 motion nor parallax. 



[The lunar eclipse of Juno 1, 1803, afforded some 

 beautiful phenomena of the kiml cles ril>ed at page 974 ; 

 and the evening being remarkably fine, was highly 

 favourable for observation. At 10.45 P.M., being the 

 commencement of the total eclipse, the limb l.v 

 showed a blood-red colour. On complete immersion, tho 

 disc was still visible, and continuetl so to the end of tlio 

 eclipse, appearing occasionally red, with a strange flicker- 

 ing appearance, like that produced by a " London fog" on 

 the sun, in November. A beautiful phosphorescence was 

 d, at 11 P.M., over the whole dise, and thin 

 alternated with a red, or rather rose-coloured tint, until 

 the reappearance of the illuminated edge. The course of 

 the phosphorescence was tho same as that of the earth's 

 shadow, for it immediately preceded both the r 

 aud emersion, aud was greatest on tho limb of the moon 

 on which each took place. In observing tlio above, wo 

 preferred tho naked eye to the telescope, so distinctly 

 were the phenomena visible. Ku.] 



