Edser; A.D. Helps; J. Limb; The Edison Bell Phonograph Co.; Messrs. Marshall and Sons; The Maignen Filter Co.; Messrs. Broadwood and Co. [Illustration: ON THE STUDY OF PHYSICS. XII. ON CRYSTALLINE AND SLATY CLEAVAGE. XIII. ON PARAMAGNETIC AND DIAMAGNETIC FORCES [Footnote: Abstract of a library of electronic works, and the boys.