In one of the plays at Hengler's Circus in London a water scene is introduced, for which purpose the main ring is flooded with water in a manner which is both striking and interesting. [Illustration: FLOODING A CIRCUS RING.] The ring is entirely lined with stout macintosh sheeting, and into this, from two large conduits. 23,000 gallons of water are poured, the tank being filled to a depth of some 2 ft. in the remarkably short time of 35 seconds. A steamboat and other small craft are then launched and the adventures of the heroine then proceed. She falls overboard, we believe, but is saved after desperate and amusing struggles. Our engravings, which are from the _Graphic_, illustrate the mode of filling the ring with water, and the steamboat launch. [Illustration: A THEATRICAL STEAMBOAT.] * * * * * SCIENCE IN THE THEATER. In the pretty little hall of the Boulevard des Italiens, at Paris, a striking exhibition of simulated hypnotism is given every evening. This entertainment, which has met with much success, was devised by Mr. Melies, director of the establishment, which was founded many years ago by the celebrated prestidigitator whose popular name (Robert Houdin) it still bears. This performance carries instruction with it, for it shows how easily the most surprising phenomena of the pathologic state can be imitated. To this effect, several exhibitions are given every evening. Mr. Harmington, a convinced disciple of Mesmer, asks for a subject, and finds one in the hall. A young artist named Marius presents himself. Mr. Harmington makes him perform all sorts of extravagant acts, accompanied with a continuous round of pantomimes that are rendered the more striking by the supposed state of somnipathy of the subject. At the moment at which Marius is finishing his most extraordinary exercises, a policeman suddenly breaks in upon the stage in order to execute the recent orders relative to hypnotism. But he himself is subjugated by Mr. Harmington and thrown down by the vibrations of which the encephalus of this terrible magnetizer is the center. When the curtain falls, the representative of authority is struggling against the catalepsy that is overcoming him. All the phenomena of induced sleep are successively simulated with much naturalness by Mr. Jules David, who plays the part of Marius in this pleasing little performance.