INSTANTANEOUS PHOTOGRAPHY. 15 



means of his adaptation of the Marey wheel, is of exceedingly great 

 interest, because, in this picture, each impression occurred at exact 

 intervals. The velocity of motion can be determined, by measure- 

 ment of the spaces separating the successive figures, with very great 

 precision, as also the relative motions of the various members of 

 the body. The advantages arising from this method of photog- 

 raphy would seem to render its further prosecution desirable, as 

 yielding a means of measurement as near scientifically exact and 

 free from sources of error as we can hope to reach. 



In 1872, Mr. Eadvveard Muybridge, of California, made the first 

 lateral photograph of a horse trotting at full speed, for the pur- 

 pose of settling a controversy among horsemen as to "whether all 

 the feet of a horse while trotting were entirely clear of the ground" 

 at any one instant of time. It was not until 1877, however, that 

 he conceived the idea that animal locomotion, which was then 

 attracting considerable attention through the experiments of Pro- 

 fessor Marey, might be investigated by means of instantaneous 

 photography, with results of probable value to the artist as well 

 as to the student of science and philosopher. 



Marey had investigated the action of a horse by fastening to 

 the shoes of the animal elastic air-chambers which were con- 

 nected by means of flexible tubes to the pencils of a chrono- 

 graphic mechanism carried in the hand of his rider. At each 

 impact of the horse's foot with the ground the compression of air 

 in the chamber caused the pencil connected with it to trace a 

 record on the revolving drum of the chronograph, and in this 

 way much valuable information was obtained regarding the rela- 

 tive action of the four feet of a horse in his different gaits. 



Mr. Muybridge proposed to carry this investigation much fur- 

 ther by means of photography. His plan consisted in arranging 

 a number of photographic cameras side by side in a line parallel 

 to a track over which an animal should be made to move, so that 

 by means of suitably arranged apparatus an instantaneous photo- 

 graph should be made in each camera of the series successively, 

 at regulated intervals of time or distance, while the animal was 

 making a complete stride or cycle of movements in front of the 

 battery of cameras. The results would then show the animal 

 in the several successive positions which he assumed in performing 

 any particular movement, and would thus furnish a complete and 



