Publications of the Leander McCormick Observatory of the University of Virginia, Volume 2The Observatory, 1901 |
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Common terms and phrases
American Meteor Society Aquarids Arc Spark km astronomers average Baker Began Ended Total camera chromospheric spectrum clouds color comet corona Date differences E. E. Barnard elements Enceladus Ended Total Meteors enhanced lines Factor Corrected Rate Fe-C Fe-V flash spectrum Fraunhofer Fraunhofer lines Geminids given HEIGHT OF CHROMO hydrogen I-Continued WAVE-LENGTHS INTENSITIES June LEANDER MCCORMICK OBSERVATORY Leonids Lick Observatory longitude maps measured moon Naval Observatory number of lines number of meteors obtained Orionids parabolic grating PARABOLIC ORBITS Perseids photographs plate rare earths Rate Remarks Station Rowland Rowland Chromo S. A. MITCHELL solar spectrum Spark km 300 spectra sphere Arc Spark sphere Rowland Rowland SPHERE SUBSTANCE Chromo strong lines TABLE I-Continued WAVE-LENGTHS Ti-Fe tion total eclipse total number UNIVERSITY OF VIRGINIA vapors WAVE-LENGTHS INTENSITIES HEIGHT writer Yerkes Observatory Zr-Fe ΙΟ
Popular passages
Page 174 - The gasses are in fact very hot, and would give their spectra of bright lines if the still brighter background of the sun could be cut off. At eclipse time the moon comes between us and the sun. As long as there is only a small portion of the sun visible, its light is so intense that the spectroscope gives the ordinary solar spectrum. At the instant that the moon entirely covers up the surface of the sun, the solar spectrum suddenly changes from a spectrum of dark lines on a bright background to...
Page 164 - ... so that the distance from sun to earth may vary- one and a half million miles on either side of the mean. Once a month, the moon revolves about the earth, but it likewise does not move in a circle so that the distance from earth to moon varies considerably on either side of the average of 239,000 miles. Moreover, the moon's path is not exactly in the plane of the ecliptic, but is inclined to the ecliptic by a small amount, a little more than five degrees of angle. An eclipse of the sun can take...
Page 33 - ... intensity. Though there are other contributing causes, the main factor for the differences in intensity between the dark- and bright-line spectra of the sun is the heights to which the vapors extend. H and...
Page 180 - 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...
Page 104 - ... are not simply due to differences of temperature. In fact we know so little about the mechanism, so to speak, of the changes of electric energy into heat, and of heat into radiation, that there is no good reason for assuming that the energy which takes the form of radiation in the electric discharge through a gas must first take the form of the motion of translation of the particles on which temperature depends.
Page 178 - ... nearer and it might arrive in time. Without looking at the sky, one realized that something unusual was happening. The light of the sun became so feeble that even the birds felt the unnatural aspect of things and sang their songs as if they were going to rest. The cocks in the nearby farm crowed. The wind, which was ordinarily blowing at this hour, was quiet. All nature was hushed. Even the seasoned astronomers who had seen two or three eclipses before felt the thrill of the unusual spectacle....
Page 180 - 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...
Page 217 - ... observations can be considered unmistakable, or in the second place has kept the same position, the conditions being the same. 3b. Under no circumstances shall a meteor be used to determine a radiant point whose projected path passes more than 3%° from the adopted point, and it is recommended that 2Vz° be generally adopted as the usual limit.
Page 108 - Among the results derived from a discussion of the 1905 eclipse spectra (op. cit., p. 494) are the following: 1. The flash spectrum is a reversal of the Fraunhofer spectrum. 2. The flash is not an instantaneous appearance, but the chromospheric lines appear gradually. At the beginning of totality, those of greatest elevation appear first, and at the end of totality remain the last. The "reversing layer" which contains the majority of the low-level lines of the chromosphere is about 600 km in height.
Page 175 - ... sunrise to sunset." Clouds, however, gathered almost every day shortly after noon, and this condition was usually accompanied by very high winds that at times rose to the strength of a mild gale. The eclipse was to occur during the middle of the afternoon, and at this time of day the skies were generally overcast. These same conditions prevailed over the whole of the western United States along the path where the astronomers were located. It was well to be an optimist under such conditions of...