Medium: Pen and ink on paper
This is a very rough pencil and ink field sketch (known as a 'foul plan') of the north bank of the River Thames, running from Purfleet, at the bottom of the map, to Upminster, at the top. The Essex landscape was described on 10 pieces of irregularly cut thin paper and shows considerable mismatching along the joins. The more detailed fair drawing OSD 133 serial 390 covers the same area. This map was made in the field by the draughtsman to augment the angle and distance measurements recorded in the Ordnance Survey field books.