PREFACE. 



I HAVE for a long time entertained the opinion that the accepted 

 theory of the relative positions of the feet of horses in rapid motion 

 was erroneous. I also believed that the camera could be utilized to 

 demonstrate that fact, and by instantaneous pictures show the actual 

 position of the limbs at each instant of the stride. Under this con- 

 viction I employed Mr. Muybridge, a very skilful photographer, to 

 institute a series of experiments to that end. Beginning with one, 

 the number of cameras was afterwards increased to twenty-four, by 

 which means as many views were taken of the progressive move- 

 ments of the horse. The time occupied in taking each of these 

 views is calculated to be not more than the five-thousandth part 

 of a second. The method adopted is described in the Appendix 

 to this volume. 



When these experiments were made it was not contemplated to 

 publish the results ; but the facts revealed seemed so important that 

 I determined to have a careful analysis made of them. For this 

 purpose it was necessary to review the whole subject of the loco- 

 motive machinery of the horse. I employed Dr. J. D. B. Stillman, 

 whom I believed to be capable of the undertaking. The result has 

 been that much instructive information on the mechanism of the 

 horse has been revealed, which is believed to be new and of suffi- 

 cient importance to be preserved and published. 



