This watercolour is a fine example of Sandby's early topographical studies. Bonnington Linn, above Lanark, is one of the three Falls of Clyde. The Clyde descends through a series of spectacular gorges, creating impressive waterfalls ('linns' in Scots) and the site became a popular attraction among tourists from the late 18th century. Sandby was a pioneer topographer and this drawing, which probably dates from the early 1750s, is important as one of the earliest depictions of a scene that went on to become so well known. The circular building, left of centre, was a dovecot which was later ruined. The falls attracted subsequent generations of artists, including Jacob More and JMW Turner.

On the reverse side of the sheet, there is a caricature of a group of men.