12 THE HORSE IN MOTION. 



artists of all degrees fell into the false and conventional manner of 

 representing animals in rapid motion, as untrue as were the Greek 

 conceptions on the subject thirty centuries ago. To understand how 

 little progress has been made in modern times, it is only necessary to 

 look at the productions of the best animal painters of our day. 



Why is it that there have been such widely different interpre- 

 tations of these movements from the time of Aristotle down to the 

 present .i* These positions, as well as all others that have been rep- 

 resented, are proved by the unerring finger of light to be incorrect; 

 as mechanical anatomy, had it been properly consulted, would have 

 demonstrated to be impossible. 



It is difficult at a glance to conceive how the eye could be so 

 deceived ; but a little consideration of the physiology of that organ 

 will teach us that no dependence can be placed on it to interpret the 

 motion of an object moving irregularly, even at a comparatively slow 

 rate of speed. 



It has been shown that the retina of the eye is capable of receiv- 

 ing a distinct image of an object in an almost inconceivably short 

 space of time, as that of the flash of an electric spark, or a millionth 

 part of a second, and that the impression remains for the space of a 

 third to a seventh of a second, according to the experiments of D'Arcy 

 and Plateau ; and the mind is incapable of distinguishing between 

 the first impression and the last made during that space of time, and 

 the images run together and are confused. A familiar illustration of 

 this phenomenon is furnished by the spokes of a wheel in motion ; yet 

 these spokes will appear stationary, if, revolving in the dark, they are 

 suddenly illuminated by an electric flash ; or if the end of a stick be 

 ignited, and moved rapidly, a continuous line of fire will appear. Here 

 there is a continuous line of impressions made upon the retina, and so 

 conveyed to the mind. The same is true of the auditory nerve; when 

 vibrations of air are too rapid, they are heard, but not distinguished. 

 The reader may ask why it is that the artists of all time, with the full 

 accord of all men, — and our own eyes confirm the tradition, — represent 

 the horse in galloping as extending his feet to the utmost, as seen in 

 all the pictures of horses racing. My answer is this: We now know 



