On the 7th of September, 1858, there occurred a total eclipse of the sun, which was also visible in South America. At Paranagua, in Brazil, it was observed by M. do Mello, director of the Imperial Observatory of Rio Janeiro; by M. Liais, a French astronomer ; and several other individuals despatched for the purpose by the Brazilian government. Several protuberances were seen. The corona appears to have exhibited a very complicated structure. The planets Venus, Mer cury, and Saturn, besides Sirius, Canopus, and three other stars, supposed to be a and /3 Centauri and a Crucis, were seen during the totality.
The hat total eclipse of the sun which we have to mention is one which occurred on the 18th of July, 1860. On this occasion, the moon's shadow first traversed a portion of the North American Conti nent ; it then swept across the Atlantic, and subsequently scoured the entire breadth of the Spanish peninsula, the eclipse terminating in the French colony of Algiers. The phenomena of the eclipse were observed by a great number of astronomers, both official and private, who had repaired to Spain for that purpose from every country iu Europe. The British government placed at the disposal of the observers from this country the steamship Himalaya, for the purpose of conveying them from England to the Spanish coast. A party consisting of between forty and fifty individuals, headed by the Aatronomer.Royal, availed themselves of this liberal offer. The greater number of the observers disembarked at Bilbao, a town in the Bay of Biscay ; the remainder proceeded to Santander, which is situate about 30 miles further west. An arrangement was made by which the observers distributed them. selves as widely as circumstances would admit over the track of the moon's shadow, with the view of guarding against casualties of the weather. A party, consisting of Captain t acob, late director of the Madras Observatory, the Rev. Dr. Mangan of Glasgow, and the writer of the supplementary matter of this article, observed the eclipse from the southern slope of the Sierra de Tolonio, a lofty mountain. range, commanding a moat extensive view of the valley of the Ebro, along which the moon's shadow was to pass. The total obscuration of the solar disc lasted 3' 20'. The planets Venus and Jupiter were seen shining with great splendour. Persons whose attention was not distracted by other matters perceived also seven or eight fixed stars. The corona was unusually brilliant on this occasion. Several rose coloured protuberances were also visible.
We shall now give a special description of some of the more promi nent features of total eclipses of the sun.
The corona of light which surrounds the dark body of the moon during the totality of a solar eclipse has been remarked by more than one ancient author. Plutarch especially refers to it in very explicit terms. Speaking of total eclipses of the sun he says :—" But even although the moon were at any time to conceal the whole body of the sun, still the eclipse is deficient in duration as well u amplitude, for there is eeen around the margin a certain brightness which prevents the shadow from being very deep." All modern accounts of total eclipses of the sun agree in describing the corona as a characteristic feature of the totality. Its light has been generally remarked to be of a pale silvery coleur,and to diminish gradually in brightness from the moon's limb. Its breadth may be said to amount to half the moon's radius, but there extend from it rays of much greater length, causing it to resemble the glory which painters in Roman Catholic countries throw around the heads of the saints.
Whatever may be the physical cause of the corona, it is very plain from the accounts of observers, that its brightness is not the same during every eclipse. Thus M. liutczycki states; that on the occasion of the total eclipse of 1850, the corona vanished at the very instant of the reappearance of the solar light. A similar statement is made by M. Moesta with reference to the total eclipse of 1853. On the other hand, in the case of the eclipse of 1860, the writer distinctly perceived the corona at least ten seconds before the totality. Certain other observers perceived it even earlier. It also continued to be visible for several seconds after the reappearance of the solar light. In conse quence of the bright light of the corolla, the darkness during the totality was not so intense as it usually is during the occurrence of such phenomena.
We shall now advert briefly to the rose-coloured protuberances seen around the moon's dark limb during the totality of a solar eclipse. These phenomena were first distinctly seen during the total eclipse of 1733, but they do not seem to have excited any interest until the observation of similar phenomena on the occasion of the eclipse of 1842 attracted the attention of astronomers to the subject. The following is a description by 31. Mauvaie of the protuberances as observed by him at Perpignan during the last-mentioned eclipse, " A few seconds after the total obscumtion, while endeavouring to measure the breadth of the corona, I perceived a reddish point at the inferior' limb of the moon, which, however, did not project sensibly beyond the limb. After an interval of fifty-six seconds had elapsed from the commencement of the totality, the reddish point ao which 1 have referred, transformed itself into two protuberances, similar to two contiguous mountains, perfectly well defined. Their colour was not uniform. Upon their slopes were seen streaks of a deeper tint. I cannot give a more exact idea of their aspect than by comparing them to the peaks of the Alpe illuminated by the setting sun and seen afar off. After the lapse of one minute and ten seconds from the com mencement of the totality, a third mountain was perceived to the left of the two others. It exhibited the same aspect as far as regards colour. It was flanked by some smaller peaks, but all were perfectly well defined. While this third mountain was in the process of issuing forth, the first two continued all the while to increase. They finally attained a height of about 2'. The interval between the two groups appeared to embrace an arc of about 25' on the moon's limb. The most considerable group, apparently the most western, seemed to we to be a few degrees to the left of the lowest point of the moon's disc." Francis Bally, who observed the eclipse from a station in the vicinity of Pavia, in Italy, remarks (' Mem. Ast. Soc.,' vol. xv.) that the protuberances resembled mountains of prodigious elevation. Their colour appeared red, tinged with lilac or purple, or rather their aspeot suggested the colour of the peach blossom. According to M. Littrow, who observed the protuberances at Vienna, their aspect, which was first white, changed to rose colour, and then to violet, and afterwards passed in a reverse order through the same tints. M. Otto Struve, who observed the eclipse at Lipesk, remarks, in reference to the rose coloured protuberances, that a very large part of the moon's disc was garnished with a similar reddish bordering.