conclusively in the year 1860, when Mr. Warren de la Rue, at Riva Bellosa, and Mr. Aguilar, at Desierto de las Palmas, by means of timing the movement of the moon on plates taken at stations 250 miles apart, settled the question finally.

The eclipse of 6th March, 1867, was not a total one, but it was signalized by the observation of a prominence by Ensign Kiha a quarter-hour before the annular phase was established-than which no better proof is possible of the brilliancy and intensity of these extraordinary objects.

In 1868, on 18th August, an eclipse was total for an unprecedentedly long period (6m. 50s.) in India, and an enormous amount of work was done--the gaseous nature of the prominences was established by several observers on the first application of the spectroscope-the work being assisted by the remarkable nature of the prominences then seen. Hydrogen gas, as expected, was ascertained to be one of their constituents.

On 20th Oct. of same year, 1868, Mr., now Sir, Norman Lockyer announced the possibility of seeing the bright lines in the solar prominences without an eclipse, and on the following day M. Janssen announced the same fact to the Paris Academy, with the further information that he had made the discovery the day after the eclipse, viz., 19th August, 1868. Truly a remarkable coincidence.

In the year 1870, 22nd December, a total eclipse in Spain, Sicily, and Africa was rendered noteworthy by the fact that the same two astronomers had curious adventures. M. Janssen made his escape from the siege of Paris in a balloon, with a special instrument for viewing the totality in Algeria, but, through bad weather, was unable to use it, for, as Miss A. Clerke says, "He reached Oran only to find himself shut behind a cloud curtain more impervious than the Prussian lines;" while Mr.

Lockyer, on the way to Sicily, was shipwrecked in the Psyche, and only succeeded in obtaining a fleeting glimpse of the wonders of the corona.

Persistent spectroscopic attacks on the prominences have revealed the fact that they consist of glowing hydrogen and some other gases, and have their source in, and rest upon, the chromospheric layer of similar gases; this consists of a thin spherical shell, covering the sun's surface everywhere to a depth of from 2,000 to 6,000 miles.

At this eclipse a further most important discovery was made, that of the "reversing layer."

The method of discovery is as follows:-Just before the second contact the dark body of the moon rapidly closes up the narrow crescent of light remaining on the sun's disc, and it finally goes out; at the very moment this happens, for a space of time not exceeding a couple of seconds, the vanishing absorption spectrum of the sun is instantly changed, line for line of the ordinary solar spectrum, into a bright line spectrum, and this wonderful appearance (not visible to the naked eye, of course) is one of the most entrancing sights among all the beauties of totality. This sight only lasts while the moon passes over about 800 miles of solar surface, which occupies only two seconds, the height of this "layer" being thereby accurately defined. This discovery was a testimony to the prescience of Kirchoff, for, as Miss Clerke says, "A ' reversing layer' or stratum of mixed vapours glowing, but at a lower temperature than that of the actual solar surface, was an integral part of Kirchoff's theory of the production of the Fraunhofer lines."

Calcium vapor was discovered in 1882, and, later, manganese, iron, and carbon (probably) have been added to

the list.

Lockyer, during the year 1900, investigated the heights

to which different gases ascend in the chromosphere, hydrogen, calcium and helium being the highest.

The theory of the corona cannot be said to be in an advanced state.

It has presented many more difficulties to the observer than the chromosphere and prominences.

It is very faint compared with the sun's light, and, although upon one or two memorable occasions it has been seen before and after totality, it has not been so amenable to investigation either by the camera or the spectroscope.

It evidently varies in intensity greatly from time to time, for it is chiefly the light which it yields that illuminates the heavens at totality, and the reports of various eclipses show great differences in its brilliancy.

It must have been very bright in 1851, when Busch, of Konigsberg, caught it upon a Daguerreotype plate.

The next successful attempt was by Mr. Brothers, at Syracuse, 22nd December, 1870.

In 1868, in India, the spectroscope was first applied to the corona, which was proved to be entirely different to the chromosphere in character.

Again, in 1869, Prof. Harkness discovered in the continuous spectrum a single green ray, which, till now, has been a subject for endless controversy. This line was so nearly identical with one of the numerous iron lines that it was then considered that this heavy metal, in a gaseous state, was evident in the corona at a distance of at least a million of miles from the sun's surface. This view, however, has subsequently proved to be erroneous.

In 1871 the sodium line was perceived as a dark line, and, at the same eclipse, Lockyer at Baikul, and Respighi at Poodacottah, perceived hydrogen in this substance 200,000 miles above the sun's surface, and established the

fact that the corona "is of a highly complex construction, being made up in part of glowing vapours, in part of matter capable of reflecting sunlight."

On 29th July, 1878, Professor Langley, at a height of 14,500 feet, on Pike's Peak, saw the corona four minutes after totality extending to a distance of ten millions of miles from the sun, i.e., more than ten times the sun's diameter in extent. This is a marvellous observation, which, though amply credited, has not since been repeated.

In 1885, Dr. Huggins made experiments with the view of photographing the corona without total eclipse; although carried out in the clear air of the Riffelberg, success was not then nor has it since been attained.

In 1887, the most extensive preparations ever made to view a total eclipse were attended by the most wide-spread disappointment; but at one place, Petrowsk, Professor Kononovitsch, of Odessa, succeeded in photographing the green line, provisionally known as 1474 K, or coronium. (for want of a better name).

Professor Ramsay, in 1895, discovered a terrestrial origin for Helium in the Norwegian Mineral "cleveite," and so settled the character of many other coronal lines which till then had not been identified.

Two total eclipses were observed in 1889-the first on 1st January from California, and the second on 22nd December from the West Indies. A well equipped party at Cape Ledo, in South Africa, from whose co-operation with those stationed in the Western hemisphere double photographs, intended to shew whether the shape of the corona underwent change in a space of two or three hours, was disappointed through bad weather.

This eclipse entailed a serious loss to astronomy by the death of the Rev. S. J. Perry, of Stonyhurst College, who was well known to students of astronomy in

this locality. Father Perry frequently attended the meetings of the Liverpool Astronomical Society, and was President for a year. (His devotion to duty was extreme, and was exemplified by the long and arduous expedition of which he took command to observe the transit of Venus at Kerguelen Island, in 1874.)

On the occasion of this eclipse he occupied a station on the Isles du Salut, near Cayenne, where there was great mortality among the convicts. Although he became dangerously ill with the epidemic, his characteristic energy enabled him to use the last of his strength to carry through successfully the important observations, after which he was conveyed on board the Comus, but did not live to reach Demerara.

The year 1896 was memorable for a new departure, in the despatch of an expedition by the British Astronomical. Association (a society numbering over 1000), of 80 of its members to Vadsö, near the North Cape. Clouds unfortunately utterly obscured the sun during the whole of totality, and frustrated the principal object of the expedition.

Their lack of fortune did not, however, prevent the despatch of another expedition, consisting of two parties, by the same society, upon a smaller scale (on account of the distance) to India for the eclipse of 22nd January, 1898. These were in every way successful (vide Indian Eclipse, 1898, E. Walter Maunder). On this occasion several important results were obtained, the most interesting perhaps being that Mrs. Maunder, on a small plate, obtained the greatest extension of the corona that has yet been photographed. One ray extending itself to a distance exceeding three-and-a-half times the sun's diameter.

The third expedition promoted by this enterprising society was divided into no fewer than five distinct parties