The great Indian eclipse of 1868 brought the important discovery that the prominences can be observed at any time without an eclipse by means of the spectroscope. In 1869 bright lines were found in the spectrum of the corona, one line in the green indicating the presence of an element not then known on the earth and hence called coronium. In 1870 the reversing layer or stratum of the sun was discovered. In 1878 a vast ecliptic extension of the streams of the corona many millions of miles both east and west of the sun was first seen. This is now known to be the type of corona characteristic of minimum spots on the sun. In 1882 the spectrum of the corona was first photographed and in 1889 excellent detail photographs of the corona were taken. In 1893 it was shown that the corona quite certainly rotates bodily with the sun. In 1896 actual spectrum photographs of the reversing layer established its existence beyond doubt--"flash spectrum" it is often called. In 1898 the long ecliptic streamers of the corona were successfully photographed for the first time. In 1900 the depth of the reversing layer was found to average 500 miles, the heat of the corona was first measured by the bolometer, and many observations showed that the coronal streamers, in part at least, partake of the nature of electric discharges. All subsequent total eclipses have been carefully observed, in whatever part of the world they may happen, and each has added new results of significance to our theories of the corona and its relation to the radiant energy of the sun. In very recent eclipses the cinematograph has been brought into action as an efficient adjunct of observation; in 1914 the first successful "movie" of the eclipse was secured in Sweden, and in 1918 Frost of the Yerkes Observatory first applied the cinematograph to registry of the "flash spectrum," and Stebbins tested out his photo-electric cell on the corona, making the brightness 0.5 that of the full moon. In 1914 (Russia) and again in 1919 (on the Atlantic) the obvious advantages of the aeroplane in ecliptic observation and photography were sought by the writer, though unsuccessfully. The photographic tests, however, conducted in preparation for these expeditions proved the entire practicability of securing eclipse results of much value, independently of clouds below. Eclipses in the near future will be total in Australia about six minutes on September 21, 1922; in California and Mexico about four minutes on September 10, 1923; and along a line from Toronto to Nantucket about two minutes on the morning of January 24, 1925.