the London Mathematical Society; American Mathematical Society; Société Mathematique de France; Deutsche Mathematiker Vereinigung; American Philosophical Society of Philadelphia; Washington Academy of Sciences; Philosophical Society of Washington; Academy of Sciences of St. Louis; Fellow of the American Association for the Advancement of Science; member of the British Astronomical Association; Honorary member of the Sociedad Astronomica de Mexico, etc., etc. He is the author of "Die Entwickelung der Doppelsternsysteme" (Berlin, 1892); "Inaugural Dissertation" at University of Berlin; "Researches on the Evolution of the Stellar System" (Vol. 1, 1896); "Catalogue of Five Hundred New Double and Multiple Stars in the Southern Hemisphere, Discovered at the Lowell Observatory," published in the Astronomical Journal (1898); and of about one hundred and fifty other scientific and popular papers in technical journals and magazines, and in the "Proceedings" of learned societies.