FIG. 7.--The Babcock and Wilcox; Messrs. Siebe, Gorman, and Co.; The Micrometer Engineering 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 commencement of.