William Gilpin was a watercolourist, vicar and headmaster of Cheam School until 1777. He is notable for being one of the first advocates of the idea of the 'picturesque'.

During the summer months, Gilpin travelled around the country, making watercolours and keeping journals in which he crystallised his personal theories about picturesque landscapes. He believed that, when drawing, an artist ought to look for the view that would most create a suitable image: one which conveyed aspects of the sublime (ruins, mountains etc) and the beautiful (light and shade, trees, pastoral scenes etc). Gilpin advocated that artistic license could be used where necessary, perhaps by adding a bridge where there was one, making ruins more ruinous or by slipping a tree into the background.
This book covers forest scenery, observed during several visits to the New Forest in Hampshire. In it he describes the different trees and shrubs to be found in the forest and how best to portray them in watercolour or in drawing and how to show them in clusters as well as singularly. There are numerous aquatint engravings and some small illustrations of branches of oak and ash, explaining how to include them in a picture.