Report of the Commission sent by the Brazilian Government to Paranagua to observe the Total Eclipse of the Sun of Sept. 7, 1858, Communicated to the Society by order of the Emperor of Brazil. (Abstract.) This Report, which has been forwarded to the Society through the Hon. William Stuart, Her Majesty's Chargé d'Affaires at the Court of Brazil, is a translation in the French language from the original. It extends to 44 pages of folio MSS. divided into sections, as follows:: 1st section, historical and introductory. 2. Observations of times of contact, exterior and interior. 3. Notes on the passage of the moon over the spots and faculæ on the sun. 4. Notes on the visibility of the moon beyond the edge of the sun. 5. On the colours of the sky, the sea, and of terrestrial objects, during the obscuration. 6. On the state of the limb of the moon, and on Baily's beads. 7. On the intensity of the light of the sun near the limb. 8. On the intensity of the atmospheric light during the totality. 9. On the corona. 10. On the protuberances. 11. Photographic observations. 12. Measures of the distances of the cusps. 13. Meteorological observations. 14. Effect of the eclipse on men and animals. The commission was appointed by the Emperor of Brazil, at the instance of M. de Mello, director of the observatory at Rio, and was ordered to repair to Paranagua as a central station. The party consisted of M. Oliveira, M. de Mello, director of the observatory, M. Liais, sent out specially by the French Government, and four naval officers on the staff of the observatory, and had a steam-corvette, the Pedro II., placed at their service. This expedition left Rio about seventeen days before the day of the eclipse, and soon after its arrival at its destination, was increased in force by several officers of the corvette who were detached for the special service. Four stations were selected, a chief central one at the country-house of Dr. Reichsteiner, the Swiss Consul, on the sea-shore near Paranagua, a second on board the corvette at sea, and two others inland at the distances of 12 and 8 leagues, situated the one near the south boundary and the other near the north boundary of the shadow. The weather seems to have been very unpromising, and rain to have been so frequent previously to the 7th of September, that little hope was entertained of success; but in the event, the excellent arrangements made were not frustrated by this cause. The position of the shore station was found to be 29° 30′ 33" 2 south latitude, by 48° 26′ 59′′ west of Greenwich. At this station there remained M. de Mello with the telescope of the equatoreal of the observatory of Rio mounted parallactically; M. Oliveira provided with an equatoreally mounted cometseeker; M. Liais, with four parallel telescopes on an equatoreal mounting common to them all, and several other observers with instruments of various kinds. The dimensions of the telescopes employed are, however, not specified with as much. fulness and particularity as is desirable. 2. The first exterior contact having been lost by the intervention of cloud at the central station, and the second interior contact having been also lost by the observers being taken by surprise, the remaining contacts noted are passed over here and left for future publication. 3. The solar spots were observed and sketched at Rio on several days preceding the eclipse; but the results are not given in the report. Much change of form and number is alone remarked. In this section the principal point noticed is that by M. Liais, who as the moon advanced over a considerable spot, noticed with a power of 300, a slight flattening of the spot in the direction parallel to the moon's limb, which appears to correspond closely with the effect noticed lately in this country during an occultation of Jupiter. 4. In the early stage of the eclipse, both M. de Mello and M. Liais were able to trace the contour of the moon to the distance of from 4' to 8' beyond the sun's limb; but the following are far more curious remarks under Section 4. With one of M. Liais's telescopes having an aperture of 3 inches, the image was observed by projection on a plate of ground glass, and the image of the moon was thus seen very distinctly, and remarked to be whiter than the neighbouring region of the sky, an appearance which lasted for some time, then became less marked, and at last not distinguishable. Some photographs of this appearance were obtained by M. Liais by the dry process on glass collodionised and albumenised, in which the effect was distinctly traced, while the plates were still wet on coming out of the gallic acid bath. M. Liais adds some remarks in explanation of the curious circumstance that both in the photographic negatives and in the projected positive image, the same effect was witnessed. The reader must, however, be referred to the original accounts for this and other matter of value which here follows. 6. M. de Mello and M. Liais were unable to perceive any mountainous irregularities in the last remaining portion of the moon's limb, or on the part which first appeared on the sun after the greatest phase, yet M. de Mello states that in spite of this circumstance, and every care in adjusting for distinct vision of the sun's limb, the phenomenon of Baily's beads presented itself to him on both the disappearance and reappearance of the sun. His telescope had 4 inches aperture and magnified 72 times. M. Liais observed these occurrences by projection, and detected no beads or irregularities. 8. At Paranagua Venus, Mercury, Saturn, Sirius, Canopus, and three other stars, supposed to be a and B Centauri and a Crucis, were seen during the totality; but M. de Mello could not trace Regulus on the meridian, although previously provided with its position. Numerical results by Rumford's photometer of the degrees of obscurity are added. 9. The corona appears by the accounts of all the observers to have presented on this occasion an unusually complicated appearance; and improbable as the details of the sketch which was sent with the account appeared at first sight, they appear to be well made out and established by the concurrent evidence of several individuals. More than three independent observers agree in testifying to the appearance of 5 distinct brushes of light reaching to an average distance of about 13' from the moon's limb, of the form of a cone with convex sides, the base equal to two-thirds the height, resting on the moon. Of these four were in their general directions normal to the moon, two on each side the vertical, and the fifth oblique, bent upwards and having its base nearly coincident with the lower normal cone on the east or apparent right-hand side. In addition to these were two brushes of white light in a strictly radial direction, one on the right, the other on the left of the vertical, and both starting out below the horizontal diameter of the moon, with a thread-like texture; and on the east or apparent righthand side of the moon an emanation of feebler light of the general outline of a parabola with its apex in contact with the dark limb. Description cannot entirely stand in the place of a figure, and the reader must necessarily be referred to a more detailed account which may probably be published hereafter. The light of the corona forming the ground on which these brighter portions were seen projected was remarked to be exceedingly unequal and patchy, and in many places to present the appearance of coarse rays crossing and intersecting in all directions, and in no part offering any exterior boundary sufficiently defined to have its termination submitted to measurement. An observation was made by M. Liais bearing on the relation of the conical brushes of light to the sun, which must be given nearly in his own words-"7 or 8 seconds after the commencement of the total obscuration, I fixed my attention on the east side on the bundle of rays forming the apparent lower edge of the oblique cone turned upwards, and which set out from the limb of the moon nearly tangentially. My attention was directed during from 15 to 20s to this bundle of rays, and on a white protuberance having a black border very near to which it passed. One of the rays in particular touched the extremity of C this protuberance, and continued backwards arrived at the edge of the moon at a distance of about 2 degrees. I witnessed this distance diminish little by little, the ray all the while remaining in contact with the extremity of the protuberance and contrasting by its brilliancy with the black border of the latter. I watched the bright (white) portion of the protuberance gradually disappear behind the moon till there remained only a minute black point which vanished about 3 seconds later. The point of intersection of the ray in question with the moon was at that instant exactly coincident with the point at which the apex of the protuberance, which had then the appearance of the summit of a lunar mountain, disappeared." A simple figure may assist this description. A RPR being the dark edge of the moon 7 or 8 after commencement of totality, Pp the protuberance with a white centre and black outline, R pr the welldefined tangential ray of the corona, the moon's edge was seen to intersect the ray at all points between R and p, as it advanced from the position ARB to a pb, when the protuberance was finally covered up, and the P R B ray was seen to intersect the limb at the point p. M. Liais argues that previous observations having connected the protuberances with the sun, and this observation indicating that the corona ray remained consistently stationary as referred to the protuberance, we may conclude that the cone of corona light of which this ray formed a part, also was an appendage to the sun and not to the moon, and by parity of reason may conclude the same for the rest. 10. Several protuberances were also seen during the totality, but they are described as having been of a white colour, and only in one instance tinged with pink. At the commencement of totality three protuberances were found on the sun's east limb, the angles of position of which counted from the lowest point (query nadir) were found by M. Liais with an equatoreal having a divided interior position circle, to be 45°, 1050, and 135° respectively. The two first were vividly white, with a black outline. On the west limb measuring, as before, from the lowest point of the disk, there were seen two others, at the angles 110° and 170°, in which a pink tint was noticeable. In a short time the protuberances on the east side were covered over, and a third one emerged on the west side (making six in all), at the angle 60°. The height of the principal protuberance on the west limb (the one situated at 110°) was twice measured by M. Liais by comparison with a fixed scale provided in the field of this telescope and estimated to be 58" at about 8 seconds after totality commenced, and 1' 18" towards the end, but these values, though probably approximate, are but estimations without the strictly corresponding times. At one of the inland stations, at Campinas, the protuberances at the angles 110° and 60° were seen to be connected by a low dentelated bank of pink light, which was not uncovered to the observers at the central station. These two protuberances with the connecting fringe appear to agree with those in the naval account from Payta on the west coast, with some discrepancy in the angular situation. There appears to be a disagreement between the indications of the letters N ESO on the sketch from Brazil, and the statement in this section that M. Liais's angles were reckoned from the lowest point of the disk. It would appear on examination that though the observers at the central station had three equatoreally mounted telescopes, the only angles read off were referred in reality to the vertical, and that the point marked north on the drawing must be taken for the true nadir point. On applying the correction 24° for the angle between the south pole and the zenith at the sun's centre, we then, from M. Liais's statement, derive the following position-angles for the 6 protuberances seen at Paranagua; 69°, 129°, 159°, 214°, 274°, and 324°, reckoned from N. round by E., the low band of pink light connecting the two last. Similarly correcting the angles read off from the sketch given in M. Le Verrier's bulletin of October 21, by the angle 82°, there result the position-angles 77o, 92°, 257°, and 342°, for the protuberances seen on the west coast, the two latter being connected by a bank of pink matter. paring these with the former, the 77° answers to the 69°, and the continuous bank from 257° to 342° with elevated terminations corresponds to M. Liais's bank from 274° to 324° similarly characterised. The angles of M. Liais are probably somewhat more exact than those observed on board the French vessel on the west coast, but they do not encourage one to enter upon any nice comparison with the angles of position of the solar spots and faculæ. Taking them as they here stand, there would appear to be no sort of connexion, which is also M. Liais's conclusion in the Report. Com II. The next section is given to an account of the means used for obtaining photographs of the disk, and of the results deduced. The length to which this abstract has already extended precludes the statement of more than that 15 photographs were taken, 9 before the totality and 6 after, of which one failed to develope, and two others were spoiled by the instrument's slipping. The positions of the cusps exhibited in this series of photographs enabled M. Liais to conclude that at the intended central station, the centres of the two bodies passed within 1"5. The remainder of the account, consisting principally of meteorological details, may be left for future and more sufficient publication. |