Collections of short articles by physicists on physics subjects, originally created with the purpose of a Festschrift for Bohr's fiftieth birthday, but intended to be humorous in nature; also contains some cartoon drawings. The preface of the first volume states: ". . . the present volume inaugurates a new periodical, exclusively concerned with the jocular aspect of the physical world." Comprised of Niels Bohr Celebration Number [Vol. I], 7 October 1935, created for Bohr's fiftieth birthday, 37 pages; Volume II dated 7 October 1945, 28 pages; Volume III dated 7 October 1955, 49 pages. Includes items by Lǒn Rosenfeld; George Gamow; Hans Bethe and Edward Teller; Victor Weisskopf.