ASTRONOMICAL ANNOUNCEMENTS BY WIRELESS TELEGRAPHY.—Prof. Kobold, editor of Astr. Nachrichten, and director of the Centralstelle, delegated the latter work to Prof. Strömgren, Copenhagen, during the war, but has now resumed it, and announces in Astr. Nach., 5044, that arrangements have been made for the distribution of astronomical information by wireless telegraphy from the Nauen station. Such messages will bear the signature “Obs.,” and it is suggested that institutions that wish to receive them should make arrangements with the wireless station nearest to them that receives Nauen messages. It is hoped that they will make a contribution to the cost of the service. The idea of using wireless in this manner is certainly a good one, and might be of great service in the case of such unexpected phenomena as the outburst of novæ, where early observations are of special value.