MODES OP PROGRESSION USED BY MAN. 137 



ficial means, the movements and the sounds of the heart, the 

 arterial pulsations, &c., and we thus proved the correctness 

 of our theories as to the nature of these phenomena. The 

 same method will serve hereafter to verify our theories of the 

 flight of insects and birds. In the present case it is necessary 

 to represent, according to the data afforded by analysis, the 

 movements of walking and of the other paces employed by 

 man. 



Every one knows the ingenious optical instrument invented 

 by Plateau, and called by him Phenakistoscope." This 

 instrument, which is also known by the name of Zootrope, 

 presents to the eye a series of successive images of persons or 

 animals represented in various attitudes. When these atti- 

 tudes are co-ordinated so as to bring before the eye all the 

 phases of a movement, the illusion is complete ; we seem to 

 see living persons moving in different ways. 



This instrument, usually constructed for the amusement of 

 children, generally represents grotesque or fantastic figures 

 moving in a ridiculous manner. But it has occurred to us 

 that, by depicting on the apparatus figures constructed with 

 care, and representing faithfully the successive attitudes of the 

 body during walking, running, &c., we might reproduce the 

 appearance of the different kinds of progression employed 

 by man. 



Mons. Carlet, whose remarkable studies of walking we have 

 before quoted, and Mons. Mathias Duval, professor of anatomy 

 at the ficole des Beaux- arts, have carried out this plan, and, 

 after manj'' attempts, have arrived at excellent results. 



Mons. Duval is engaged in perfecting his diagram, which 

 furnishes to the eye sixteen successive positions for each kind 

 of locomotion employed by man. Each figure is carefully 

 drawn according to the results afforded by the graphic method. 

 When rotated with suitable speed, the instrument shows, with 

 perfect precision, the different movements of -walking or run- 

 ning. But its principal advantage is that, by turning it less 

 quickly, we cause it to represent the movements much more 

 slowly, so that the eye can ascertain with the greatest facility 

 these actions, the succession of which cannot be apprehended in 

 ordinary walking. 



