by RONALD PAULSON , author of works on Hogarth, Rowlandson and other 18th-century subjects. In the 1720s a literary kind of garden was evolved in England by writers such as Addison, Pope, Shenstone and Vanbrugh. Professor Paulson singles out the gardens at Castle Howard in Yorkshire and Stowe in Buckinghamshire to show the way such gardens operated on the visitor. followed by an interlude