Page:Popular Science Monthly Volume 57.djvu/23

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THE COMING TOTAL ECLIPSE OF THE SUN.

tails of the corona itself; they burn out very near the disk by over-exposure while the faint outer extensions are being taken. Wet plates having the requisite quickness are harder to prepare,

PSM V57 D023 North american tracks of all the total eclipses in the 19th century.png
Chart VI.—Tracks of the Eight Total Eclipses of the Sun seen on the North American Continent during the Nineteenth Century.

but are smoother and hold the coronal rays better from the base to the outer edge, and there is always plenty of time to give the necessary exposure. The No. 26 Seed plate requires from 0.5 to