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. 



No. 7. M. Londe 's apparatus with multiple objectives, 1883. — Return- 

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

 M. Londe, aided hy 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 consequently 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 by 

 a similar method anal}zes the phases of the motion of torpedoes. 



No. 8. Multiplication of the number of pictures : 1. Partial photo- 

 graphs. 2. Dissociation of the images bef 'ore the dark field. 3. Photo- 

 graphs on a film ribbon in motion, 1887-88. — A perfect analysis of 



Fk;. 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 riot being thereby 

 accelerated, the result will be that the photographs will be taken so 

 close together that they 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 body of the subject, but only certain 

 points or lines w T hose 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, w T ears 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. 



