(δια and ὁράω, view), a mode of painting and of scenic exhibition, by which landscapes, and architectural and other objects are represented with the most perfect degree of optical illusion. The diorama is an imitation of the panorama, which was invented by Barker, an English artist, about 1796, and afterwards greatly improved in France. The first diorama was exhibited by MM. Daguerre and Bouton at Paris in 1822. The painting, which in the panorama is cylindrical, in the diorama is prepared on a plane surface. The management of the lights is a most important part of the exhibition. Various means are employed to enhance the illusion by optical combinations, such as transparencies, coloured glass, the light of torches, screens, &c.; and the differences of reflected and transmitted light afford an almost infinite variety of effects. By such means the transitions from day to night, and all the varied tints of sunshine and shadow, are imitated with a degree of illusion that is almost magical. The spectator is introduced into a chamber from which light is excluded, and sees through a large aperture or proscenium a view that is sometimes of great extent, and which is illuminated with all the effect of reality. The illusion is sometimes enhanced by several adjuncts, such as music, the singing of birds, the sound of rushing water, &c.