No. h. m. h. m. m. s. 1. At 1 30 Greenwich M. T. = 7 27. Local M. T. the duration is 1 12.6 2. ” 1 35 ” ” = 7 47. ” ” ” ” ” 1 19.6 3. ” 1 40 ” ” = 8 05. ” ” ” ” ” 1 26.0 4. ” 1 45 ” ” = 8 22. ” ” ” ” ” 1 31.7 5. ” 1 50 ” ” = 8 40. ” ” ” ” ” 1 37.0 6. ” 1 55 ” ” = 8 54. ” ” ” ” ” 1 41.9 [Illustration: CHART III.--FIFTEEN PICTURES OF THE SOLAR CORONA, ARRANGED IN THE ELEVEN YEAR PERIOD, TO SHOW THE RECURRENCE OF SIMILAR TYPES DURING THIS PERIOD.] An observer at the intersection of these cross-lines with the central line will see the totality during the intervals given in the table. The mode of the formation of the shadow cones of the moon, called the penumbra for the partial shadow and the umbra for the total shadow, are well illustrated in general works on astronomy, and good geometrical pictures of them can there be found, together with much useful information regarding the subject of eclipses. As we are here concerned chiefly with certain practical points about the eclipse of 1900, it will be well for the reader to consult such works for many details regarding the astronomical features attending an eclipse of the sun which must now be omitted. There are many existing theories to account for the phenomenon of the sun’s bright appendage, called the corona, which is visible only during eclipses, on account of the absorbing effects of the earth’s atmosphere on its light. Is it electrical, or is it magnetic? Is it composed of fine stuff ejected from the sun, or of meteoric dust falling upon the sun? Is it merely an optical effect, as some suppose, or is it a portion of the newly discovered radiant matter streaming off to enormous distances into space? The answer to these questions is eagerly sought through observation, photography, and every other possible means, on the occasion of each total eclipse.