Page:Popular Science Monthly Volume 57.djvu/23

Rh 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,



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