Its walls, though of only moderate altitude, are distinctly terraced. HAGECIUS. The most westerly member of the Vlacq group of formations. It is situated on the S.W. of Rosenberger, and is about 50 miles in diameter. The rampart on the E. is continuous and of the normal type, but on the opposite side is broken by a number of smaller rings. WEST LONGITUDE 40 deg. TO 20 deg.
BIELA. A considerable ring-plain, about 55 miles in diameter, S.W. of Janssen, with a wall broken on the N.W., S., and E. by rings and large enclosures. There is a central mountain, but apparently no other details on the floor. ROSENBERGER. This formation, about 50 miles in diameter, is one of the remarkable group of large rings to which Vlacq, Hommel, Pitiscus, &c., belong.
Imp. de St. Pétersbourg, t. vi., col. 77. Von Dr. Nach., No. 3,267; Observatory, vol. xviii., p. 64; F. H. Seares, Astr. Corr., vol. xxv., pp. 3-22. Reprinted by Zöllner. See Bull. R. A. S., vol. x., p. 376. Rosenberger calculated no more, though he lived until 1890. Month. Report. Brit. Imp. de St. Stars seen through the tail, October 18, lost much of their lustre.