With its beautiful colours and precise depiction, it is easy to forget these are highly technical drawings – as well as works of art. This one in particular illustrates the plans for a new drainage tunnel, as well as the position of the shield. The print itself was done in September 1836, therefore showing the progress of the Thames Tunnel at that point. Pencil mark corrections show new developments dated up to January 1837. The old shield is also depicted, which had to be replaced halfway through construction. The dark circles on each side of the light blue Thames reference the horse ramps which were never built.