The upward motion of the protuberances in process of formation is sometimes very rapid. Some protuberances have been observed to ascend in the solar atmosphere at the rate of from 120 to 497 miles a second. Great as this velocity may appear, it is nevertheless insignificant when compared with that sometimes attained by protuberances moving in the line of sight instead of directly upwards. Movements of this kind are indicated by the displacement of the bright or dark lines in the spectrum. A remarkable instance of this kind occurred on the 26th of June, 1874. On that day I observed a displacement of the hydrogen C line corresponding to a velocity of motion of 1,600 miles per second. The mass of hydrogen gas in motion producing such a displacement was, according to theory, moving towards the Earth at this incredible rate, when it instantly vanished from sight as if it had been annihilated, and was seen no more. Until recently the protuberances had not been observed to rise more than 200,000 miles above the solar surface; but, on October 7th, 1880, a flame, which had an elevation of 80,000 miles when I observed it at 8h. 55m. A. M., had attained the enormous altitude of 350,000 miles when it was observed at noon by Professor C. A. Young. If we had such a protuberance on the Earth, its summit would be at a height sufficient not merely to reach, but to extend 100,000 miles beyond the Moon. Although the solar protuberances represented in Plate II. have not the enormous proportions attained by some of these objects, yet they are as characteristic as any of the largest ones, and afford a good illustration of the purely eruptive type of protuberances. The height of the largest column in the group equals 4' 43", or a little over 126,000 miles. A large group of Sun-spots was in the vicinity of these protuberances when they were observed and delineated. TOTAL ECLIPSE OF THE SUN PLATE III A solar eclipse is due to the passage of the Moon directly between the observer and the Sun. Such an eclipse can only occur at New Moon, since it is only at that time that our satellite passes between us and the Sun. The Moon's orbit does not lie precisely in the same plane as the orbit of the Earth, but is inclined about five degrees to it, otherwise an eclipse of the Sun would occur at every New Moon, and an eclipse of the Moon at every Full Moon.