Cirro-cumulus cloud which occurs in summer in warm dry weather. Shown over the River Thames, London, England. In right foreground is a typical Thames sailing barge. The bridge is Blackfriars, designed by Robert Mylne (1734-1811), built 1760-1769 and replaced 1860-1869. St Paul's Cathedral is in the centre of the picture. From 'The Beauty of the Heavens' by Charles F Blount (London, 1845). Coloured lithograph. Photo via Newscom