The Optical Magic Lantern Journal (November 1901)

86 The Optical Magic Lantern Journal and Photographic Enlarger. will be seen just ready to begin his aerial journey. Then the part of the slide indicated by the dotted line a (Fig. IV.) will be seen; the man will be at the beginning of the rope. ‘The sliding glass is then pushed slowly through the framework. What is the result? The string pressing against the wheel of the barrow will cause it to revolve. The pivot fixed to the wheel will revolve with it, and thus pull the connecting rod c backwards and forwards.. The effect of this movement on the man is obvious. His legs will be caused to cross each other as in the action of walking. All these movements—the people moving away from the performer, the string passing under the wheel of the barrow, and the action of walking imparted to the man—seen on the screen by the audience will lead them to the belief that the man is actually walking across the tight-rope, whecling his barrow before him, and leaving the applauding spectators and the merry clown behind him on his journey. A reference to the apparent flight of objects viewed from a train in motion will render this point quite clear and decisive. When he has reached the end of his perilous journey the man is caused (by the operator simply pulling the sliding glass back through | the grove) to recross the rope, this time back| wards. These evolutions, as seen on the screen, are very effective, and by pushing the glass through the framework rapidly the operator can make the man run across the rope with his barrow, thus considerably heightening the effect. sabe >< Some Principles of Cinemato graphic Machines. By E. D. ROMs Se THOUGHT it would interest the Ox Ni readers of this journal to give a 1c description of the various devices Voy that have been used from time to ‘wy =) = time for the intermittent feed of the film in cinematographs—forming probably the essential details of the cinematograph—and also some other mechanical details for effecting intermittent movement ; the intermittent movement having in almost every case to be obtained from a constantly rotating shaft. Fig. I. shows a form -of the well-known Geneva motion, in which the operation is as follows:—c is the | a partial movement to the wheel pb. driving-wheel receiving its motion from a continuously rotating shaft a, and B the shaft having imparted to it an intermittent movement. c and D are respectively the driving and driven-wheels, the shape of c being such that portions of its periphery are curved so as to correspond with the curvature of the ends of the teeth & upon the wheel pv. The wheel c has projections F projecting beyond its periphery and arranged so that during its rotations it engages in the notch G and gives Motion thus is only given to the wheel p when the projection F strikes the sides of the tooth x, no rotation being imparted to the shaft B as long as only the curved periphery of the wheel C is in co-operation with the curved edges of the teeth &. Thus, as it is shown in Fig. I. , ' not only is an effective intermittent movement obtained, but the wheel p is locked, while the shaft B is stationary. Fig. II. shows a method by Panhard, of Paris, and in this instance the film uz, having the usual perforations, passes down a guide. A reciprocating slide r has a pawl G mounted upon it, opened by link u, rocking lever p, connecting rod c, crank pin B, mounted upon the constantly rotating shaft, a. By these means, as the shaft a is rotated the slide a is caused to reciprocate, and as the slide moves upwards the pawl c is allowed to run free; but as soon as the slide begins to return the pawl engages with the perforations on the film and draws a given length of film, the movement of the slide being adjusted either by the eccentricity of the pin B or the point at which the connecting rod c is joined to the rocking arm pb. Tig. III. shows another metbod of operating the film, and although the method of taking hold of the film is similar to the last case, yet the results are brought about in a different manner. A triangular-shaped tappet a recip