New York / London: Longmans, Green / Edward Arnold, 1919. Blue cloth. pp xii, 276. Index. Ex Franklin Institute Library, with spine label, label inside front cover (Bloomfield H. Moore Memorial Fund), perforations in title leaf, pouch and label at rear; else a VG clean, tight and unworn copy. At time of publication Crowther was University Demonstrator in Experimental Physics in the Cavendish Laboratory, Cambridge. ; Octavo