The Optical Magic Lantern Journal (December 1901)

102 The Optical Magic Lantern Journal and Photographic Enlarger. in Fig. III.; s corresponds to the fixed glass c3in Fig. IV. We will now refer to Fig. III. more definitely, in order to consider the method of fitting up the donkey. The two front legs o are cut out of one piece of thin wood, and glued to the fixed glass s. The head and body H are cut out of a piece of thin metal, and pivoted to the front legs by the stationary pivot s. It will be noticed that the donkey's back is so cut as to leave a slightly projecting piece rR, which serves as a saddle. It goes without saying, of course, that the donkey is so fitted up that the boy will appear to be really sitting on its back. In the donkey’s body will be noticed a semi circular slot. Its use will be seen later. The legs x and tail m are pivoted to the body at the | In this diagram z is a small | points L and k. projecting part of the donkey’s body turned up at right angles to the body, and prevents the » legs N from swinging too far forward. Upon the surface of the centre sliding glass, opposite that to which the boy is attached, is | glued a small block bearing a pin p, which | works in the semi-circular slot in the donkey’s | body. The dotted line Qin Fig. III. indicates the position of this block with reference to the donkey. The pin vp is shown working in the slot. Before the action of the slide is verbally explained, it may be as well to briefly state the purpose of each of the diagrams. Fig. L., then, shows the boy with the wheel glued to his body, and thread passing round the wheel. Fig. Il. isa sectional diagram of the movable glass, showing more clearly the manner in which the boy is attached to it by means of the small block F. Fig. III. shows all the working parts of the donkey, and the method in which they are fitted up. Fig. IV. represents a sectional view of the three glasses alone, with no parts attached to them. Fig. V. is a sectional diagram of three glasses, showing the manner in which all the working parts are fitted up and their relation to one another. In this diagram it may be necessary to state that w represents the thread on which the boy revolves, and v is one of the blocks at the ends of the fixed glass to which are secured the ends of the thread. Fig. VI. shows the attitude the donkey takes up when the sliding glass is pushed in half way. Let us now see what takes place when the centre movable glass is pushed in. Reference being made first to Fig. III., it will be seen that the pin p would slide along the semi-circular slot, and, in so far as the donkey is pivoted at J, , cause it to throw up its hindguarters a little. The legs n.and tail m would move up also. When the sliding glass is pushed half way, or, in other words, when the pin p has progressed half way along the slot in the donkey’s body, the donkey will have thrown up its hind legs to their fullest extent, and will have assumed the attitude shown in Fig. VI. Then, as the sliding | glass is pushed further still, the pin Pp will move right along the slot, and the donkey will descend again. “If the sliding glass be now pulled back, the donkey will repeat its evolutions. But at the samme time as the donkey is kicking up its hind legs, the boy upon its back is, by reason of the fact that the sliding glass to which he is indirectly attached is being shifted, caused to partly ‘turn over” along the stationary thread. It thus appears as though he were being thrown off the donkey’s back. When the sliding glass is