APPEND. A.] SPECTROSCOPIC OBSERVATIONS OF THE SUN. 213 Committee early in 1867), in order that the coincidence in time between his results and those obtained by the Indian observers might not be misinterpreted. "Details are given of the observations made by the new instrument, which was received incomplete on the 16th of October. These observations include the discovery, and exact determination of the lines, of the prominence spectrum on the 20th of October, and of the fact that the prominences are merely local aggregations of a gaseous medium which entirely envelopes the sun. The term chromosphere is suggested for this envelope, in order to distinguish it from the cool absorbing atmosphere on the one hand, and from the white light-giving photosphere on the other. The possibility of variations in the thickness of this envelope is suggested, and the phenomena presented by the star in Corona are referred to. "It is stated that, under proper instrumental and atmospheric conditions, the spectrum of the chromosphere is always visible in every part of the sun's periphery: its height, and the dimensions and shapes of several prominences, observed at different times, are given in the paper. One prominence, three minutes high, was observed on the 20th October. "Two of the lines correspond with Fraunhofer's c and F; another lies 8° or 9° (of Kirchhoff's scale) from D towards E. There is another bright line, which occasionally makes its appearance near c, but slightly less refrangible than that line. It is remarked that the line near D has no corresponding line ordinarily visible in the solar spectrum. The author has been led by his observations to ascribe great variation of brilliancy to the lines. On the 5th of November a prominence was observed in which the action was evidently very intense; and on this occasion the light and colour of the line at F were most vivid. This was not observed all along the line visible in the field of view of the instrument, but only at certain parts of the line, which appeared to widen out. "The author points out that the line F invariably expands (that the band of light gets wider and wider) as the sun is approached, and that the c line and the D line do not; and he enlarges upon the importance of this fact, taken in connexion with the researches of Plücker, Hitorff, and Frankland on the spectrum of hydrogen-stating at the same time that he is engaged in researches on gaseous spectra which, it is possible, will enable us to determine the temperature and pressure at the surfaces of the chromosphere, and to give a full explanation of the various colours of the prominences which have been observed at different times. The paper also refers to certain bright regions in the solar spectrum itself. “Evidence is adduced to show that possibly a chromosphere is, under certain conditions, a regular part of star economy; and the outburst of the star in Corona is especially dwelt upon." As regards the claims of priority of this discovery, all will feel inclined to agree with the following eloquent words of M. Faye when speaking on this subject in the French Acadamy on October 26, 1868 :— "Mais au lieu de chercher à partager, et par conséquent à affaiblir le mérite de la découverte, ne vaut-il pas mieux en attribuer indistinctement l'honneur entier à ces deux hommes de science qui ont eu séparément, à plusieurs milliers de lieues de distance, le bonheur d'aborder l'intangible et l'invisible par la voie la plus étonnante peut-être que le génie de l'observation ait jamais conçue?" As this work passes through the press, another great discovery is announced (Proc. Roy. Soc. Feb. 11, 1869), by Mr. Huggins, who has devised a method by which the form of the solar prominences can be viewed without an eclipse, so that the investigation of the rapid changes which these flames undergo becomes now a simple matter of observation. APPENDIX B. EXTRACTS FROM THE REPORT OF THE COUNCIL OF THE ROYAL ASTRONOMICAL SOCIETY TO THE 49th ANNUAL GENERAL MEETING. Solar Eclipse of 1868, August 18. "The results obtained by the different observers are of such interest and importance that the principal observations which would not otherwise appear in our 'Transactions' are given in considerable detail in the observers' own words. "It is with great satisfaction that the Council call the attention of the Fellows of the Society to the complete success of their own expedition;-a success for which the Fellows are much indebted to the skill and energy of the Superintendent, Major Tennant. The Astronomical Society's Expedition. "It will be in the recollection of our Fellows that at the last Anniversary Meeting it was stated that preparations had been made at the recommendation of the Council of our Society for the observation of the Total Eclipse of the Sun in India. The Astronomer Royal took a warm interest in the proposed observations, and addressed the Secretary of State for India on the subject. It was ultimately arranged that the expense of the expedition should be borne jointly by the Government of India and the Imperial Government. The superintendence of the expedition was entrusted to Major Tennant. It is with great satisfaction that the Council is able to announce that Major Tennant has been most deservedly and eminently successful. The Report of Major Tennant's observations is now in the hands of the Society, and it is intended that it shall appear in the forthcoming volume of the Transactions,' fully illustrated with facsimiles of the photographs taken at Guntoor, which it is proposed to enlarge photographically, in order that the details of the prominences may be seen more clearly than is possible in the small copies which accompany the paper. Mr. De la Rue, who evinced considerable interest in the expedition, and afforded facilities to Major Tennant for familiarizing himself with astronomical photography before he started, has undertaken to see that the photographs are properly enlarged and copied. "It is here proper to state that to Major Tennant is due the credit of having first called attention to the peculiarly favourable conditions which would be presented by the Solar Eclipse of August 1868.1 "It is only justice also to mention that, as far as regards the part which England took in the observations, it was mainly attributable to the energetic, active, and untiring zeal of Major Tennant, who happened to be in England on leave during the greater part of 1867, and who devoted much time in promoting the observations which, in spite of many difficulties, have been so successfully undertaken and carried out. "It will be recollected that Major Tennant, after consulting with the Astronomer Royal and other Fellows of the Society, undertook the following work. It was most comprehensive, and entailed possibly almost too much responsibility for the director of a single expedition. "1. The determination of the geographical position of the station. This was successfully accomplished by means of a repeating circle, although, in consequence of bad weather, there were not many available days between the arrival of the observers and instruments at Guntoor and the day of the eclipse. 1 Monthly Notices, vol. xxvii. pp. 79, 174. The position was found to be, Latitude N. 16° 17′ 29′23′′, and "Captain Branfill, R.E., subsequently connected the station with the marks of the Great Trigonometrical Survey, and deduced the following result: Lat. N. 16° 17′ 34:3′′, and Long. E. 5h. 21m. 46·5s. "2. Spectroscopic Observations. These were undertaken by Major Tennant himself, by means of the Sheepshanks equatorial, of 4·6 inch aperture and 5 feet focal length. This had been mounted equatorially by the late Mr. Cooke, and was suitable for all latitudes in the British Isles, but it had to be altered to suit the more southern stations of India. The spectroscope employed with the telescope was made by Messrs. Troughton and Simms, and was provided with a scale of equal parts, which was illuminated by means of a lamp. The addition of this spectroscope threw additional work on the driving clock beyond that for which it was originally calculated, and, in consequence, some difficulties were experienced just at the critical time of observation from the irregularity of its going. "In spite, however, of this and other mishaps, Major Tennant was able to carry out his observations, and ascertained, 1st, that the corona only gave the continuous solar spectrum; 2d, that the light of the prominences was resolvable into certain bright lines of definite refrangibility, showing that these appendages consist of gaseous matter at a very high temperature. Major Tennant states that the Great Horn gave a beautiful line in the red, a line in the orange, and one in the green, which appeared multiple, also a line seen with difficulty near F; he says the red and yellow lines were evidently c and D: the reading of the bright line coincides with that of the brightest line in b. The line near to F was, in all probability, F itself; E, he says, was certainly not seen by him, and that, as regards the line in the blue, it was useless from his data to speculate upon it. "We now have more precise information from the researches of M. Janssen and Mr. Lockyer respecting the position of the bright lines, and the probable nature of the Sun's appendages; but it must be admitted that Major Tennant did this part of his |