Since my report on the Dark Ring Nebula in Cygnus,1 I have received the following communication from Dr. R. H. Curtiss, Acting Director of the Detroit Observatory of the University of Michigan: "Your article in the February Popular Astronomy on a dark ring nebula in Cygnus has led me to look up an excellent slide which we have of that region made from a photograph secured with the 6-inch Willard Lens on October 5, 1893, at Lick Observatory. The dark elliptical ring stands out very beautifully on this slide. I think anyone would notice it but would be strongly tempted to ascribe it to a defect in one of the pieces of glass through which light must pass in making the lantern slide copy.”
Proceedings of the Iowa Academy of Science
©1927 Iowa Academy of Science, Inc.
Morehouse, D. W.
"The Dark Ring Nebula in Cygnus,"
Proceedings of the Iowa Academy of Science, 34(1), 273-275.
Available at: https://scholarworks.uni.edu/pias/vol34/iss1/70