This drawing instrument is a Kern ‘drop’ compass which was used to draw a range of features including roundabouts, circuses and gas holders. The parallel pen attachment, seen here, was used for ink work, the line weight being set with the adjustable blades. Unlike a conventional compass, the drawing arm could be lifted off, or lowered onto, the drawing material while the point remained in position. This made it the ideal tool for drawing the small sections of arc necessary to form a roundabout between the joining roads. It also came with a separate graphite lead attachment.