Model of Maskelyne's 6ft Mural Circle (by Troughton). Wooden base board, in which are sunk two viewing wells, one for each circle, and steps. Two walls, with the mural circles suspended on the inner sides, facing one another. The walls are imitation stone, and the models painted black. With one of the circles, is a mercury bath. Wooden viewing platform with steps set each side between the two circles. Two figures, one standing on the viewing platform and the other lying on an observing chair in one of the wells.