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THE TOTAL SOLAR ECLIPSE OF 1918
States Navy who was to watch the chronometer and count the seconds. This signal summoned each man to his post. One last look was given to the apparatus to see that everything was in place, the plate holders were adjusted— and then we waited. "Two minutes" before was called out, and then "one minute," still again "thirty seconds" before the expected time of totality. The clouds by this time had thinned considerably, the patch of blue sky was only a short distance away. The plan had been that after the signal of "thirty seconds" there should be nothing said until the word "Go" told that the total eclipse had begun. I was to watch for this with a pair of binoculars, before one glass of which a direct vision spectroscope had been arranged. But due to the thin clouds at the beginning, it was impossible to see the spectrum lines with the spectroscope, and the signal "Go" was actually given by Mr. Hammond who was using the five-inch telescope. No sounds disturbed the work of the party except the call of the seconds as the time passed, and the brief words of command and the shift of plate holders as each member of the party did his allotted task. Ten seconds after totality commenced, the clouds, thin at the beginning, had still further thinned, and at mid-totality the conditions were even further improved. What a gorgeous spectacle then met the eye! The sun was now in a very thin wisp of cloud with blue sky on either side. Although the cloud would detract from the scientific results, still it greatly enhanced the pictorial effect. The corona could be seen stretching for a short distance from the sun's edge, but most remarkable of all were three great tongues of flame, one immediately at the top of the sun, one on the left-hand edge, and still a larger one on the right edge of the sun. These shone with a brilliant scarlet light, and made the eclipse of 1918 memorable as the eclipse of color. As the end of totality ap
proached the thin clouds became still thinner-and two minutes after the eclipse was over the sun had reached the blue patch of sky. If the eclipse had occurred only two minutes later, or if the party had been only half a mile to the northwest, the sky conditions would have been perfect! If the eclipse had taken place fifteen minutes earlier, the scientific results would have been nothing at all. The optimists had won
The developed photographs exhibit the painstaking care of the astronomers in procuring the precise focus with the result that all of the photographs show exquisite definition. The thin clouds did not interfere at all with the details of the prominences or flames surrounding the sun. Those taken with the sixty-five foot camera exhibit the prominences in splendid detail on a scale where the sun is more than seven inches in diameter. The longer exposures for procuring the extensions of the corona were not quite so successful since the thin, fleecy clouds cut down the fainter streams of coronal light. The smaller cameras showed the same results as the larger ones-splendid detail in the inner corona, but the corona not of very great extent. All the photographs unite in showing many polar rays, and they also exhibit some plumed arches of great beauty. The corona was of the sunspot maximum type, but with more polar streamers than were expected.
The spectroscopes procured photographs of exquisite definition, but these photographs suffered also from the clouds which cut down the amount of exposure that at best is none too great.
What was perhaps the most interesting piece of scientific work accomplished at the 1918 eclipse owes its conception to Mr. Edward D. Adams, of New York, who has shown his great interest in science by the founding of the Ernest Kempton Adams fellowship which is awarded each year by Columbia University for researches in the do
main of pure science. Upon becoming a member of the United States Naval Observatory party, Mr. Adams took upon himself the responsibility of trying, by some method, by photography, by a drawing, or by a painting, to procure a reproduction which would show the beauties of the corona, and which should be true not only as to form but more especially as to color. Unfortunately for science, it is impossible to obtain a satisfactory representation of the corona and the sun's surroundings by photography. The corona is very brilliant near the edge of the sun, but the intensity fades very rapidly. The eye can take cognizance of the details in spite of the great changes in brilliance, but not so the photographic plate. To obtain the faint extensions of the corona which are readily visible to the naked eye, a comparatively long exposure is necessary. This long exposure causes so much overexposure in the brighter inner regions of the corona that all detail there is lost by being burnt out. Short exposures give us the inner corona in exquisite detail, but the outer corona is then lost through shortness of exposure. Many attempts have been made to cut down the relative exposure by means of mechanical devices -but none of these have been entirely successful. Heretofore, the only success in representing the corona has been obtained by taking photographs with different times of exposure and with different cameras in order to procure photographs with detail both in the inner and brighter parts of the corona, and in the fainter outlying portions. After the eclipse is over, a composite drawing is usually made from the examination of different photographs. This method has given several satis
factory drawings, but they still have left much to be desired. However perfect they may have been as drawings, they took no note of color. Mr. Adams took upon himself the task of finding the right man to draw and paint the corona. Color photography could not help out in procuring the right color, and there was left only the possibility of finding an artist who would have the true scientific spirit, and who could combine an accurate sense of form with a refined perception of color. Mr. Adams was successful in finding Mr. Howard Russell Butler, a portrait painter of note, who has developed a shorthand method of noting both form and color.
During the eclipse, Mr. Butler sat on a lofty perch overlooking the eclipse instruments, and from which he could obtain a fine view of the sun. The task he had taken to himself was no small one. And moreover this was the first corona he had ever seen!
Those who were privileged to see Mr. Butler's picture at the American Museum of Natural History pronounced it a painting of rare beauty. The astronomers who saw the 1918 eclipse and who have seen the picture look upon it as a marvel of perfection, true both as to form and color, a work of art which has the added advantage of being scientifically accurate.
The scientific world owes a great debt of gratitude to Mr. Butler for his exquisite corona, but even a still greater debt to Mr. Adams, through whose conception, generosity, and enthusiasm the painting of the corona became possible. One ventures to predict that this splendid painting will cause the recent total eclipse of the sun to be known as "Color Eclipse of 1918."
INSTRUMENTS ADJUSTED AND EVERYBODY READY, UNITED STATES NAVAL OBSERVATORY STATION, BAKER, OREGON
The first two tents cover powerful spectroscopes and under the third are two cameras. The horizontal tube of the 65-foot camera is seen in the background. Five of
The members cf the observing party, naming from left to right, are as follows: Dr. Mary M. Hopkins, associate professor of astronomy, Smith College; Dr. S. A.
Painting the Solar Corona
By HOWARD RUSSELL BUTLER, N. A.
Illustrations from drawings which give the artist's records made at the time of the eclipse and explain his method of work; also from the artist's paintings of the phenomena of the eclipse, color plate opposite, and frontispiece in color "Total Eclipse of the Sun, June 8, 1918," opposite page 245
N May, 1918, I received an invitation from Mr. Edward D. Adams, well known as a patron of science and art, to accompany him to Baker, Oregon, where the United States Naval, Observatory had established its station' for observing the total solar eclipse of June 8, 1918. Professor S. A. Mitchell, director of the Leander McCormick Observatory of the University of Virginia, and Mr. Adams had agreed that a painting of the corona might be made which would have both scientific and artistic interest.
Many drawings and countless photographs (some colored by hand) have been made of solar coronas, but I was told that no record existed of any, painting actually made from direct observation. The invitation was therefore accepted as a unique opportunity.
As a portrait painter I have usually asked for ten or twelve sittings of twohours each: now I was asked to render my subject in 112 seconds. The method of procedure therefore became all-important.
The first step was to study the reports in astronomical and popular works of previous eclipses and thus familiarize myself with all attempts to describe or record the form and color of the corona and prominences. Of these attempts there are a great number. They describe an outer corona, varying in extension from a fraction of a diameter of the moon to many diameters, the color usually being described as pearly and variously tinged; an inner corona, more brilliant than the former; and the prominences of incandescent hydrogen, variously described
as red, ruby colored, pink, and bloodred. In addition to these, my picture would have to show the dark surface of the moon, and the sky with whatever color value it chanced to have at the moment of observation.
As regards the shape and the extension of the outer corona, a theory exists that it varies inversely in size as the combined area of sun spots, and this seemed to be confirmed by about twenty drawings of previous eclipses, which I made from photographs and prints. and reduced to the same scale. Thus in the eclipse of 1900, when sun spots were at a minimum, the corona exhibited wide extensions, having interesting shapes, two of which became known as the "Angel Wing" and the "Herring Tail" extensions. As the number and size of sun spots seem to vary quite regularly, so that the maximum is reached about every eleven years, and as we were near a maximum period, wide extensions of the outer corona were not to be looked for. We expected about three fourths of a diameter on each side and this is about what
All reports of the so-called "inner corona" agree that the part nearest to the sun is very brilliant and this inner corona is usually described as whitish in color. The transition from this inner portion to the far less brilliant outer part is quite abrupt, but one of the questions on which there seems to be a difference of opinion concerns an absolute demarcation between the inner and the outer coronas. I found none.
As regards the prominences-while often discernible with the naked eye, it