The next attempt at photographing the corona was on August 18, 1868, this being remarkable as the first attempt to use a reflector for the purpose. Colonel Tennant and Sergeant Phillips at Guntoor used a 9–inch silver-on-glass mirror, by With, of 6 feet focal length, mounted equatorially by Browning on the Newtonian plan.
Unfortunately the weather was unfavorable, but plates were exposed through light clouds, the longest exposure being 10 seconds. The photographs obtained show the prominences sharply defined, but only slight traces of corona are visible. Mr. Sutton, at Mautawali Kiki, and Drs. G. Fritsch, H. Vogel, and W. Zener, at Aden, were, from atmospheric and other causes, unsuccessful with refractors.
At the eclipse of August 7, 1869, many attempts were made to photograph the corona. In all cases where the image was enlarged before it fell on the plate, slight traces of the corona were obtained; while Professor Winlock and Mr. J. A. Whipple, at Shelbyville, with a 5½-inch lens of 7½ feet focal length, obtained seven pictures taken in the primary focus, one with 40 seconds’ exposure, showing more detail than had previously been photographed.
At this eclipse, Messrs. Hoover photographed the corona with a lens of 12 inches focus, and Professor Stephen Alexander also obtained photographs at Ottumwa some of which give good ideas of the coronal structure.
At the 1870 eclipse, December 22, a 4–inch Dallmeyer lens (rapid rectilinear), stopped down to three inches aperture, and with a focal length of thirty inches, was used by Mr. Brothers at Syracuse. Wet plates were used, and the photographs were taken through light clouds, the best of the pictures having had eight seconds’ exposure. Details in the corona are very well shown in these photographs. In discussing his results, Mr. Brothers says, “The photographs taken ... prove that the light of the corona is very actinic, and that several photographs of this beautiful phenomenon can be taken during the time of totality.” He further adds, “That it is impossible to obtain satisfactory photographs of the corona either with reflecting or refracting telescopes as ordinarily used is, I think, now conclusively proved.”
Professor Winlock, at Jerez, during the same eclipse, obtained two good photographs with ordinary telescopes; while Lord Lindsay, at Maria Louis Observatory, with a 12–inch mirror of 6 feet focus, obtained plates so much fogged as to be useless.