HISTORY OB^ CHRONOPHOTOGRAPHY. 329 



No. 16. Analyzing and projecting chronophotograph, Marey, 1898. — 

 The writer has pushed the improvement of his chronophotographic 

 apparatus, so as to obtain perfect equidistance of the views, and has 

 succeeded in doing- so while preserving the main principle of not 

 perforating the films. For perforation, besides wearing, so as no 

 longer to bring the pictures around regularly, also occupies a zone of 

 T V of an inch (2.5 mm.) on each edge of the ribbon, a loss which is 

 more important the narrower the film. The writer has succeeded in 

 obtaining perfect regularity in exposures by modifying the first pair of 

 rollers which takes the film. The apparatus is shown in tig. 19 (PI. Jl). 



In making projections, a further difficulty arose, namely, the posi- 

 tive film undergoes some shrinkage in the successive developments 

 requisite to obtaining it, in consequence of which the pictures, being 

 too near together, pass by too soon, and tend to leave the field of 

 the screen. A simple drag or brake upon the magazine spool corrects 

 this fault. Positive ribbons of different breadths were exhibited, 

 showing the sharpness and equidistance of the photographs. 



No. 17. Microscopic chro,nophotography, 1899. — The writer has 

 adapted the chronophotograph to the study of motions which take 

 place in the field of the microscope. In order to avoid exposing the 

 animals studied to the heat of an intense illumination, an arrangement 

 was adopted in which the shutter-disk only effects the lighting up of 

 the preparation during the time of exposure, which is about one- 

 five-hundredth part of a second. This done, the brightest light no 

 longer produced any injurious effects. Numerous photographs were 

 exhibited, together with the instrument. 



.No. 18. Chronopliotogvajyhic gun with a film ribbon, 1899. — In its 

 original form the photographic gun only gave twelve views. For a 

 more extended series an instrument of a new type (fig. 20, PI. II) 

 was constructed, in which the successive photographs are taken on a 

 band 6Q feet (20 m.) long. The shutter is formed of a light-cock, 

 which is far less cumbrous than a disk. In the stock of the gun is a 

 clockwork moved by a dynamo. Whenever the trigger is pulled the 

 circuit is closed and the film begins moving, and does not stop until 

 the trigger is let go. Light accumulators, or a portable pile, furnish 

 the necessary current. 



PART II. 



SCIENTIFIC APPLICATIONS OF CHRONOPHOTOGRAPHY. 



Animated projections, interesting as they are, are of little advan- 

 tage to science, for they only show what we see better with our own 

 eyes. At best, they serve to slow a motion which is too quick for 

 direct observation, or to accelerate it if its extreme slowness causes us 

 to miss some of its features. 



