A NUMBER of further observations of Halley's comet are recorded in Nos. 4415–8 of the Astronomische Nacbrichten. In No. 4416 (p. 401) Prof. Max Wolf gives a sketch showing the position of the tail on May 12 at 14h. 15m. (Königstuhl M.T.). A slight curvature was noted, the convex side being towards the north, and the extremity of the tail lay on a line joining α Equulei and β Aquarii. From this observation it was deduced that the actual length of the tail was about 45 million kilometres (28 million miles), whilst that part through which the earth would pass, if passage took place, was at least 3° broad. Observations extending from May 17 to 24 indicate that the halos observed at the Konigstuhl Observatory on May 19 were more than twice as strong as those observed on the other days. Dr. Cerulli directs attention to an apparent shortening of the tail towards 15h. (M.E.T.) on May 18, which he ascribes rather to the alteration of direction, in regard to the line of vision, than to the approach of daylight.