cases, had journeyed from afar to execute previously planned details in a great and comprehensive design.

Of the observational methods employed time forbids me to speak, and compels me also to recount only in the briefest way what I judge to be most important among a host of interesting and extremely valuable results.

I should explain that at present the chief subjects for investigation during a total solar eclipse are: the nature, composition, and general structure of the corona, that pearly, luminous àppendage which bursts into view around the eclipsed sun during the brief time the moon's shadow cuts off the solar light from our atmosphere. True, then there also appears the chromosphere, an inner zone of glowing crimson gases lying immediately over the photosphere, the brilliant white surface whence comes our sunlight. And there are also the prominences, marvellous crimson flame-jets, often towering many thousands of miles above the chromospheric stratum. However, as these last-named features can be spectroscopically seen and photographed on any clear day without waiting for an eclipse, the corona, which so far has refused to depict itself except during totality, comes in for chief attention. Incidentally I should mention the reversing layer, the thin stratum of metallic vapors underlying the chromosphere, wherein originate most of the familiar dark lines in the solar spectrum. Latterly, however, means have been devised for photographing this interesting region more at leisure than during the instants before and after totality, when, by previously known methods, it could only be observed. Thus, as already pointed out. the corona is the chief objective of astronomers' attacks; and to photograph it with as much detail as possible, as also to record photographically the characteristic lines of its spectrum, is what is chiefly desired.

I wish I could fully describe to you all the admirable work accomplished on June 8th, spite of trouble with clouds. But I can only summarize in a very brief way a few of the more striking. results. It must suffice to say that plates taken with the larger type of photo-telescopes show long coronal jets extending out

beyond the sun's limit to at least three solar diameters, or about 12,000,000 km. Some plates record strange curved rays resembling the petals of a flower. A skilled observer who watched the corona visually, tells us its color was pale green, and its structure like the petals of a lily. He believes this last-named appearance is due to crossing currents in the corona. He counted seven of these leaf-like forms, each towering above the sun for several millions of miles.

Five bright coronal lines were recorded by the spectrographs, and their wave lengths accurately determined later. These are as follows: 5,303, 4,231, 4,086, 3,987, 3,601.

Other fainter lines have been perceived on the plates, but not with sufficient clearness to admit of measurement. It was further proven that the corona also gives a continuous spectrum in which the solar dark lines do not appear, thus demonstrating that it is self-luminous and does not shine by reflecting sunlight. The bright lines above mentioned are not coincident with those of any element or substance known to us at present. However, we may expect that with the accurate determinations of wave-length now available, identification with some possibly new element, or perhaps constituent of one of our present elementary or simple bodies, should be only a matter of time.

I regret it is not possible to speak of a great many minor observations, all interesting and valuable in their way. I need hardly remind you that Dr. Chant, a past-president of the Society, and Editor-in-Chief of its JOURNAL, was good enough to undertake the long journey to Matheson, Colorado, where he successfully photographed the corona, and also made some observations as to polarization of the coronal light. As we were favored with an account of his work after his return, this brief mention of it must suffice now.

Attention was given to the investigation of what are termed the shadow bands, and even the crescent-shaped solar images formed by the light passing through apertures between the leaves of trees were watched for and photographed. Beyond doubt the, eclipse observers accomplished excellent work, and their efforts

will prove to have greatly extended our knowledge in the vast domain of solar physics.

Now, leaving the sun, I will speak briefly of work accomplished in the line of planetary study. All the important planets of our system came into positions favorable for observation during 1918, and same were presented under exceptionally advantageous conditions.

I will not detain you with any account of observations of the two inner planets, Mercury and Venus; and indeed I have failed to meet with reports of any new or valuable work done in that connection. I therefore pass on to speak of Mars, which for many reasons may be regarded as the most interesting member of our system. As you doubtless know, the planet Mars comes into opposition at intervals of a little more than two years; consequently we see it under conditions favoring observation of its surface marking every alternate year. Its 1918 opposition occurred about the middle of March last, and though our distance from it at that epoch was quite considerable and consequently its angular diameter small (about 15′′), its north declination was a compensation, and the most interesting hemisphere, the northern, was turned earthward during its spring and summer seasons. Our atmospheric conditions also seem to have been generally good, consequently numerous observations were secured and we are being favored with reproductions of many accurate and carefullymade drawings which show beyond question changes evidently due to seasonal succession and climatic conditions. Interesting as are these results, I cannot dwell upon them. I must, however, point out that the reality of those very singular surface markings, often strangely resembling geometrical figures, the existence of which only a few years ago was doubted, and even bluntly denied, is now conceded on all hands, and has been made the subject for several explanatory theories. The presence of water on Mars, in spite of the low temperature theoretically prevailing at its surface, is being more and more widely admitted as alone capable of explaining many of the observed phenomena. Indeed, Professor W. H. Pickering, who, next to the lamented late Percival Lowell,

has long been the most assiduous student of the Martian features, among American astronomers, constantly speaks of "marshes", "flooded areas", "snowstorms" and "hoar frosts", not to mention "clouds" and "fogs", and explains changes of color in the "deserts" as due to the thawing of frozen surface-soil. He has further recently advanced a hypothesis which assumes a meteorological origin for the so-called canals, which he believes are effects produced by prevailing rapid winds accompanied by rainfalls. A host of other interesting observations might be cited, did our time allow. While anxious to shun invidious comparisons, I must say that in my own opinion the admirable designs we owe to the skill and patience of Professor Mentore Maggini, of Florence, made during the recent opposition, are the most realistic and excellent I have met with hitherto. So admirably and faithfully has this observer depicted the Martian surface details that anyone familiar with the telescopic appearance of the planet will instantly recognize each particular region and admit the fidelity with which it has been portrayed. Pickering, who is giving careful consideration to observational work done by several amateurs, lays stress on what he recognizes as a demonstrated fact, that for Martian study a very large aperture is not only unnecessary, but may even be a disadvantage. In my own humble way, I have tried to emphasize the utility of small telescopes for that particular work. I trust that at the next opposition of Mars all our members who are possessors of telescopes will not fail to give at least some measure of attention to the study of our most interesting planetary neighbor.

While much might be said in connection with observations of the great exterior planets, Jupiter and Saturn, I will confine my review to pointing out that the visible surfaces of both these bodies. evidently consist of zones which have different rotational rates. This fact has not been so fully demonstrated in the case of Saturn as in that of the great Jovian planet; however, differences in the Saturnian rotation period as determined by several good observers can only be explained on that supposition. I believe the unique observation made in 1917 by Messrs. Ainsley and Knight, who saw

an occultation of a sixth magnitude star by the outer ring of Saturn, the star remaining visible, though reduced in light, while behind the ring, has not since been duplicated. Doub.less during the several months when it is well placed for observation, occultations of stars by Saturn occur from time to time, and might well be made the subject of watching by amateur observers.

Spectrographic observations of Jupiter and Saturn, while showing several absorption bands, have failed to demonstrate the identity of any of these with bands due to water vapor.

The results of planetary photography are becoming more satisfactory, and we may not unreasonably indulge in the hope that ere long such greatly improved photographs of Mars, Jupiter and Saturn will be secured as will admit of their profitable study. under considerable magnification.

Before leaving the solar system, we may note that only a few small telescopic comets appeared during 1918.

I referred to the appearance of a conspicuous Nova in the constellation of Aquila, as one of the two most noteworthy astronomical events of the year. I already mentioned that by a curious, though, of course, entirely fortuitous, coincidence, it was first seen (at least by astronomers in America) on the evening of June 8th, the day on which occurred the total solar eclipse. Several persons in England, France, and other European countries claim to have seen it earlier, some saying June 6th, others June 7th. However, on a photographic plate of that region of the sky taken at Harvard Observatory on the latter date, it appears as a small star of only the sixth magnitude; so the claims just mentioned could only be reconciled with the undeniable photographic evidence by assuming that the Nova flashed out briefly and suddenly declined, which would be quite an abnormal and previously unheard of occurrence. However, on June 8th it had increased in brightness enormously, 10,000 times, considerably exceeding the first magnitude, being, in fact, the brightest Nova since Kepler's famous star. Its color was at first an intense bluish-white, but as it declined in lustre it became yellow, ruddy, red, and at last dull greenish white. The falling off in brightness was at first very rapid, but afterwards.