XI. Preliminary report on the results obtained with the prismatic cameras during the total eclipse of the Sun, April 16, 1893

During the total eclipse of 1871 observations were made by Respighi and myself with spectroscopes deprived of collimators, and a series of rings was seen corresponding to the different rays emitted by the corona and prominences. The phenomena were so distinct that I made arrangements for a repetition of the observations during the eclipse of 1875, and an instrument, which received the name of “prismatic camera,” was arranged to photograph the rings. The chief advantage of the instrument is that it combines the functions of a telescope with those of a spectroscope, and gives spectroscopic views of the solar surroundings in each radiation. The object-glass employed on this occasion had an aperture of 3 3/5 inches and a focal length of 5 feet, while the prism had a refracting angle of 8 degrees. Two photographs were obtained, showing several protuberances in addition to continuous spectrum from the: corona. I again employed this method of observation during the eclipse of 1878, but failed 1 to see the rings, the corona apparently giving only a continuous spectrum.