Swans Down tube cake pan, patented Dec. 18, 1923 and manufactured by E. Katzinger Co., Chicago. There are two versions of this pan, and this is the larger size, 8 3/4" across and 3 3/4" high. The center tube rises about 1 1/2" above the pan.
The inside reads "Swans Down Cake Flour Makes Better Cakes, Made in USA. There are 2 side vents which can be opened slightly, I presume they are helpful in unmolding the finished cake. One of the two opens easily, the other does not. The pan shows moderate wear and minor rust.
This pan comes from a farmhouse in rural Pennsylvania.