The Optical Magic Lantern Journal (February 1901)

bo bo be familiar with it. wheel or ball, but also, through the revolution of the wheel, the movements of the dog. Perhaps it would be as well if at this point the fitting up of the dog be described. The component parts necessary for its construction are shown in Fig. IIT. the head, 2 the body, 4, 9 and 10 the legs, and 3, 6, 7 and 8 the necessary connecting links. 11 is a small staple whose use will be seen later. All these parts are made of thin metal except the body, which is made of wood. The wood must be nearly equal in thickness to the combined thicknesses of the support block and wheel (Fig. V.), so that the working parts may be on a level with the action rod (Fig. V.). The body is now glued to the fixed glass in the proper position, and the other parts pivoted and connected to it as shown in Figs. II. and IV. The head 1 is pivoted to the body at a, and pivoted to the link 8. The link 3 is pivoted also to the longer link 6. The leg 4 is pivoted to the body at B, with the foot almost touching the top of the wheel or ball =. It must not, however, quite touch the wheel or its motion would’ be impeded, but upon the screen it appears to, and that is all that is needed. The leg 4, the link 6, and the link 3 are pivoted together at the same point. The link 6 is pivoted to the body at c, and at its lower extremity to the leg 10 and the link 8. The leg 10 is also with the other leg 9 | pivoted to the body at p. The leg9 is pivoted to the link 7, which is in turn pivoted at its other extremity to the link 8. There now remains to be described the action rod 13 (Figs. II. and V.). This is pivoted to the wheel at H, and passing through the staple 11, which is soldered to the leg 4, is pivoted at its other extremity to the link 6. It is especially important here, as it not only causes the revolution of the | 1 represents ; The Optical Magic Lantern Journal and Photographic Enlarger. | The sham leg 12 (Figs. II. and IV.) should now be painted upon the fixed glass in black, when the slide will be completed and ready for exhibition. I will describe its action as the sliding glass is pushed in and out. Particular reference will be made to the Figs. II. and IV. When the string F in Fig. II. is pulled from left to right, the wheel would in consequence be turned in a direction opposite to that of the hands of a clock. The action rod 13 would thus be pushed upwards as in Fig. 1V. This would cause the link 6, and also the link 3, to be raised a little, and the dog’s head, being pivoted at a, would thus be thrown forward. At the same instant, the leg 4, being pivoted to the body at B and to the links 8 and 6, would be caused to move back from right to left till it registered exactly over the painted leg. Also, in consequence of the link 6 being pushed up, the links 7 and 8 would contract as in Fig. IV., and cause the legs 9 and 10 to cross one avother as in the action of walking. The dog will, in fact, assume the position shown in Fig. IV. Then, when the string Fr is further pulled, the action rod 13 will descend again and cause the dog to reassume the attitude shown in Fig. II. That is to say, the head will be thrown up, the leg 4 will be pushed forward in the action of rolling the ball along, and the legs 9 and 10 will again cross asin the action of walking. Thus, when the slide is exhibited upon the screen by means of the lantern, and the sliding glass pushed in or pulled out as the case may be, the spectators painted thereon will pass by the dog, who goes through the motions of walking on his hind legs and rolling the ball along with his two front legs; and so the dog will appear to be actually walking along, pushing the ball in front of him. When the sliding glass reaches its limit the clown will appear in sight, and it will thus seem as though the dog has gone through his performance in obedience to his commands. If the glass be then pushed or pulled back, the dog will appear to walk backwards, rolling the ball back with him, an even more difficult trick than the former. In conclusion, it should be mentioned that owing to its horizontal nature the movement of the string is not visible upon the screen, and the string is itself rendered to a large extent unnoticeable by the lines drawn on the sliding glass representing the ground.