There is ample scope for the presentation of an illusion with a number of moving animals. All that is necessary is that they should be kept fairly well together with their legs in various moving attitudes. This illusion is perfectly managed by many of the French painters of battle scenes in the nineteenth century, notably Horace Vernet,[a] Gros,[b] Chartier,[c] Morot,[d] and Meissonier.[e] The action in the cavalry charges of Morot and Chartier is amazingly true to life. Even three or four animals will suffice for an illusion,[f] but this cannot be provided with the smaller animals, as sheep or goats, because although a series of progressive actions may be given to those outside animals in a flock whose legs are visible to the spectator of the picture, the scale to which they are painted is necessarily so small that the eye has an entirely insufficient range for operating the illusion. Where several horses are represented as moving at considerable speed, it is necessary that some of their feet should touch the ground, otherwise the illusion is destroyed, or else the animal may appear to be racing through the air.[g] The effect is not so disturbing when all the feet of the moving animals are on the ground,[h] or where they are hidden by herbage,[i] or where all the animals are on their hind legs,[j] though in these instances an illusion is almost impossible. [a] La Smalah at Versailles. [b] The Combat of Nazareth. [c] Jena, 1806, and Hanau, 1813. [d] Reichsoffen. [e] 1814. [f] Rosa Bonheur's Ploughing in Nivernois. [g] Fromentin's Couriers des Ooled Nayls, Luxembourg; Schreyer's The Attack, N. Y. Public Library; and Gericault's Epsom, Louvre. [h] A. Brown's The Drove. [i] Uhde's Cavalry Soldiers Going into Action, Muffel Collection. [j] Snyder's Hunt, Munich Gallery. In cases where horses and men are crowded together, and are struggling in confusion, it is only necessary in order to provide an illusion, that no action should be entirely separated from the others. There was a fine example of this work in a lost drawing or painting of Titian, of Pharaoh's Host Overwhelmed in the Red Sea[a]; and many artists of the Renaissance produced like illusions in pictures of the rape of the Sabines. Where the movement is spread over a large area, and the scale to which the animals are drawn is comparatively small, the various groups engaged must obviously be connected together in a series. Franz Adam arranges a scheme of this kind in a battle scene, using running soldiers or hauled guns as links in the chain.[b] [a] An engraving on wood by A. Andreani is in existence. [b] A Bavarian Regiment before Orleans, Munich.