HISTORY OF CHRONOPHOTOGRAPHY. 



323 



nomical revolver of Janssen, with this difference, that it produces 

 pictures about 800 times more frequently, which calls for a pretty deli- 

 cate mechanism. Fig. 9 shows the photograph of a gull in free flight. 



XtK 7. J/. Londe'' s apjxiratus ^oitli inuJtipIe ohjecfives^ i^^^J.— Return- 

 ing to the method of Muybridge, with a very important improvement, 

 M. Londe, aided by M. Dessoudeix, constructed an apparatus in which 

 a series of twelve objectives form their images upon different parts of 

 a rectangular plate of large size. An ingenious arrangement causes 

 the successive opening of these objectives at equal intervals as short as 

 may be desired. The analysis of the motion is consequent^ very per- 

 fect. The order of the images can not be deranged, since they are all 

 obtained on one plate. But the number of pictures is limited by the 

 necessity of having a separate objective for each. General Sebert bj^ 

 a similar method analyzes the phases of the motion of torpedoes. 



No. S. Multiplication of the numher of pictures: 1. Partial plioto- 

 graphs. 2. Dissociation of the imag eshef ore the darl' field. 3. Photo- 

 graphs on a fllin rihhon in motion, 1887-88. — A perfect anah'sis of 



Fig. 10. 



Fig. 11. 



motion requires that the photographs be taken at as short intervals as 

 may be, yet for as long a time as possible. If we merely make the 

 rotation of the shutter-disk faster, the number of images will, it is 

 true, be augmented, but the animal's locomotion not being thereby 

 accelerated, the result w'ill be that the photographs will 1)0 taken so 

 close together that the}' interfere with one another and produce the 

 confused effect seen in figure 7. A first way of avoiding this confusion 

 is to photograph, not the entire bod}- of the subject, but only certain 

 points or lines whose position is significant of the facts we desire to 

 know. A man dressed completely in black (fig. 10), and consequently 

 Invisible upon the dead-black background, wears certain bright points 

 and lines, strips of silver lace attached to his clothes along the axes of 

 his limbs. When this man, so rigged, passes in front of the apparatus, 

 photographs will result that will be accurate diagrams to scale (fig. 

 11), showing without confusion the postures of upper and lower arms, 

 thighs, lower legs, and feet at each instant, as well as the oscillations 

 of the head and of the hips. The method also allows the play of the 

 joints to be studied. 



