Draft letter, from Sir John Herschel to William Radcliffe Birt, dated at Collingwood Rough draft version of the following item in Herschel's hand. John Frederick William Herschel's theory of barometric waves. Comparison with ocean tides. Notes the important of large waves. Compares to an advancing form and a molecular movement, with a two-fold motion of each particle, vertical and horizontal. Mentions invariable dynamical connexion. Birt's note of Brussels "wind-rose" or law of periodicity of winds at Brussels is worthy of attention. 28 July 1843