Continuing with deceptions dependent upon exceptional external arrangements, we may find in conjuring tricks simple and complex illustrations in great perfection. When wine is turned into water, when two half-dollars are rolled into one, when a box into which an article has just been placed is immediately opened and found to be empty, when a handkerchief is torn and made whole again, when the performer drives a nail through his finger, when a coin suddenly appears out of space at the end of a wand, when a card which you have just assured yourself is the ace of hearts on second view is the king of spades, when a bowl filled with water in which goldfish are swimming is produced from under a handkerchief, when a child rests horizontally in mid-air supported only on one elbow,--you are misled or mystified or deceived in so far as you are unaware that the wine was potassium permanganate and sulphuric acid, and was clarified by sodium hyposulphite; that the one half-dollar is hollow and the solid one fits into it; that the box has a double bottom controlled by a secret spring; that the real handkerchief was not torn but another substituted for it; that the nail has been replaced by one that fits around the finger; that the wand is hollow, and a spring controls the appearance or withdrawal of a split coin at its other end; that one half of the card is printed on a flap which, by falling down, shows another aspect; that the bowl covered with a rubber cap was secreted under the coat of the performer; that the child wears a steel suit fitted with joints that lock and become rigid. All these are technical devices which amuse us by the ingenuity of their construction, and, though they may be most baffling, provoke about the same type of mental interest as does a puzzle or an automaton. Ignorance of this technical knowledge or lack of confidence in its existence may convert these devices into real deceptions by changing the mental attitude of the spectator. However, the plausibility of such performances depends so much upon their general presentation that they seldom rely for their effectiveness solely upon the objective appearances presented. They are given a dramatic setting, or put forward as examples of newly discovered forces or of magical control; and this makes them far more effective than this bare account would suggest.