There is a general belief that the protuberances do not change their form, at least but slowly, so it is of great consequence to substantiate my statement, which is, that whilst waiting for No. III. plate this protuberance shot out, and when No. III. photogram was taken it had lost its flamelike appearance, and about one-third its height. No IV. photogram shews the great prominence much reduced in height and increased in breadth, as if it had tumbled into a heap of burning matter. I cannot say whether all prominences are formed by the shooting-out of a flame, and then tumbling into a heap, but I do say that the great protuberance was formed in that manner. In looking at the Des Moines photogram, taken near the end of the eclipse, (I don’t mean the engraving,) you see a great heap, not very unlike that seen in No. IV.; and Dr. Curtis remarks “that there is the same appearance of vast volumes of matter tossed up into an irregular heap by the ejecting force, and sinking back again. on all sides in long vertical rolls.” This is a very good description of what actually took place. Unfortunately, the long exposure of sixty-six seconds gives a softened appearance, and what should have appeared as a heap of cinders, now looks like a fluid.
I now come to the most remarkable photogram that has ever been taken of an eclipse. No. IV. was taken as near the limb of the sun as it is possible to take one, for on shutting down the slide, out burst the sun. In this photogram you can see two luminous concentric bands running from A to E, separated by a dark space, or rather a dark band, which takes its origin on a part of the protuberance A. (See fig. 3.) These bands are crossed by numerous bright rays, all parallel to themselves and to the protuberances A and E. There are two bright beams, and both, together with the bright rays, are divided by this dark band. At E is seen the protuberance with a triplicate form, and appears to be three parallel planes of light; upon the upper one there appears a dark line, similar to those seen upon fig. 3. Now, on looking at the Des Moines photogram, you actually see the stumps of these three parallel planes; could anything be more satisfactory? I will leave it to others to discuss these various phenomena, which will throw much light on the physical constitution of the sun, but will recapitulate some of the facts deduced from our observations. The corona belongs to the sun, and not to the moon. Some of the protuberances are formed by the shooting of a flame, which burns out, leaving something that looks like a cinder, which crumbles into a heap, and then retains that form for some time; that there are luminous gases that surround the sun in concentric strata divided by a non-luminous layer; that the notches on the limb of the moon are the reflections of the upper part of the protuberances from the surface of the moon; that at a great distance from the sun there is a violent current of gas in an opposite direction to the motion of the sun upon its axis; that the light band surrounding the moon’s limb in photograms of the partial eclipse, may be caused by the reflection from the second or under side of the plate.
In conclusion, I congratulate those gentlemen who so kindly assisted me on our complete success, especially my dear friend and old ship-mate, Professor Stephen Alexander, without whose assistance no Canadian party would have been formed; and also, Mr. Vail, of Philadelphia, who kindly joined our party, and whose annexed report gives such ample proof of the value of our negatives.
E. D. Ashe,
Commander, Royal Navy,
Director Observatory, Quebec.
June 22nd, 1870.