Original vintage optical industry trade magazine ad for JAMES G BIDDLE SCIENTIFIC INSTRUMENTS. Main office and factory was located in Philadelphia, PA.  Fahy Experimental Permeameter.  Many educators in charge of physics instruction are realizing that a more adequate grasp of the underlying principles of magnetism is properly due to all students, not necessarily only to those whose courses aim to prepare them for the technical and engineering professions.  The Experimental Permeameter's primary purpose is the cover laboratory and demonstrative work that will give the student a firm grasp of first principle.  Old 1922 old medical laboratory industry advertisement.