A Barge approaching a Glacis, near Ning-po, China

William Alexander was one of the official draughtsmen to Lord Macartney’s Embassy to China in 1792, part of an attempt by the British Government to open up trade links. Alexander’s task was to provide finished watercolours for the official account of the voyage. ‘Glacis’ is military terminology meaning ‘mound’, and was used here to refer to the sloping surface down which the barge is about to descend to the lower level of water. The Chinese used these devices instead of locks and lock gates, to manage canal navigation. A print based on this drawing appeared as an illustration in Alexander’s ‘Costume of China’, published in 1805.