Cols--the power is constantly varying, owing partly to the Alps. Thither, to an essay of Mayer's, entitled 'Beitraege zur Dynamik des Himmels,' Heilbronn, 1848; 'Bemerkungen ueber das Mechanische Equivalent der Waerme,' Heilbronn, 1851. ==================== IN MEMORIAM.--Dr. Julius Robert Mayer died.