THE QUARTERLY JOURNAL OF SCIENCE. OCTOBER, 1870. I. THE ECLIPSE OF AUGUST 7, 1869.-" ANVIL" PROTUBERANCE. By W. S. GILMAN, jun., New York. THOSE who observed the solar eclipse of last August with a sizeable telescope will not soon forget the startling effect produced by the appearance of the large oval protuberance on the western limb of the moon. We were unusually favoured as to atmosphere at our station near Sioux City, Iowa, and when in addition to this it is stated that our observations were made by the aid of a 4-inch refractor-one of Mr. Alvan Clark's best-it will not seem strange that the details about to be recorded were so readily obtained. The "anvil" protuberance, for such the object is recorded in my notes, was seen by one of our party several moments prior to the totality. Several months' study of the sun's surface had prepared me to expect the more remarkable protuberances in the southern hemisphere, and having selected the south-western quadrant as an especially favourable locality, from the presence of faculous ridges near the limb two days prior to the eclipse, the bright "anvil"shaped mass instantly attracted my attention. Its extraordinary brilliancy enabled me afterwards to keep it in view when a considerable crescent of the reappearing sun had rendered the corona invisible. A hasty glance at other portions of the moon's limb satisfied me that the "anvil" protuberance possessed greater interest than any other, and I therefore devoted my whole time to its consideration, except so much as was employed in obtaining several outline sketches of the corona. In a forecast of the probable positions of protuberances, which I made on August 5 (see Fig. 1), the double prominence at A occupies very nearly the position of the object under discussion. In Fig. 2 we have the appearance of the sun's disc on the same day, and near that part of the limb subsequently occupied by the "anvil," we notice a cluster of bright faculous spots. It was the 2 H VOL. VII. intense whiteness of these objects that led me to suppose there might be hovering above the solar surface in this region gaseous exhalations that would appear during the eclipse. The white meridian in this second diagram represents the limb of the sun for the 7th of August, and it will be noticed that the cluster of faculæ is just beyond this line. A similar white meridian in the diagram giving the appearance of the sun on the 9th of August (Fig. 3), indicates the eastern limb of the sun during the eclipse. In this latter instance we have the faculous ridges marked I, G, F, E, which may be referred to prominences 4, 5, 6, and 7 of Prof. Mayer's diagram. It is worthy of special notice that the faculous masses at I are very irregularly disposed, the tortuous windings of its parts suggesting whirling motions in the photosphere. Prof. Mayer's "Eagle" prominence is a fit object to hover over such a curiously-agitated portion of the solar surface. That my sketch gives a correct representation of the windings of these ridges of faculæ I feel quite confident. While making the observation the outline was likened to a rude drawing of a camel (Fig. 4). The resemblance may appear to some if the page is inverted, the camel being supposed to face to the left. Fig. 5 is a copy of my sketch of the spots on the sun's disc, as they appeared an hour previous to the eclipse. There was little or no change in their form or position until after the close of the phenomenon. The large spot near the eastern limb, enveloped in a platform of faculæ, is the same as that visible on the 9th (Fig. 3) near the same locality. ance. I was particularly impressed with the stability of the protuberIt resembled a monstrous white-hot coal, and its outline DIAGRAM SHOWING SPOTS ON THE SUN DURING THE was sharp and well defined. The appellation "rosy protuberance struck me at the time as a misnomer. I detected only bright fireorange tints, like the glowing coals of an anthracite grate, with delicate crimson flakes of surprising brilliancy scattered over the southern part. These flakes stood out against the bright background as if totally disconnected from the rest of the phenomenon. In the plate I have endeavoured to give their positions and the direction of their axes, which latter coincided with the stratification of the protuberance. I should estimate the length of these brilliant dashes of crimson light at from 3" to 5". Possibly in a future eclipse a momentary spectrum of them may be obtained, as their extraordinary brilliancy may make amends for their minute size. The plate accompanying this article was prepared from my observations of the great protuberance, with the exception of the outline of the mass, which was obtained from the last Ottumwa |