178 ANIMAL MECHANISM. 



so that e;icli horse is drawn half on this sheet, and the other 

 half on that which is placed beneath. The hind quarters, 

 for example, having been drawn on the upper sheet, the fore 

 quarters are drawn on the under sheet, and are visible through 

 the portion cut out of the upper sheet. Let us suppose that 

 we cause the upper paper to slide as far as the interval which 

 separates two figures of the horse, we shall have a series of 

 images in which the fore limbs will full back a certain dis- 

 tance towards the hind limbs. We shall thus represent, 

 under the form of pictures, what is obtained under the form of 

 notation, by slipping the two lower slides of the notation rule 

 one degree. And as this displacement to the distance of one 

 degree for each of the movements of the hinder limbs gives 

 the notation of the broken amble, we shall obtain, in the 

 figures thus drawn, the series of the successive positions of 

 the paces of the broken auible. If the paper be made to slip 

 a greater number of degrees, we shall have the series of atti- 

 tudes of the horse at his walking pace. A still greater dis- 

 placement will give the attitudes of the trot. 



In all these cases, these figures, when placed in the instru- 

 ment, make the illusion complete, and show us a horse which 

 ambles, walks, or trots, as the case may be. Then, if we 

 regulate the swiftness of the rotation given to the instrument, 

 we render the movements which the animal seems to execute 

 more or less rapid, which will permit the inexperienced 

 observer to follow the series of positions of each kind of pace, 

 and soon enable him to distinguish with the eye a series of 

 movements in the living animal which appear at first sight to 

 be in absolute confusion. 



We hope that these plates, though still somewhat defective, 

 will soon bo sufficiently perfect to be of real use to those who 

 are engaged in the artistic representation of the horse. 



After these studies of terrestrial locomotion, we ought to 

 explain the mechanism of aquatic locomotion. Some rect-nt 

 experiments of Mons. Ciotti have thrown great light on the 

 propulsive action of the tails of fishes; not that they have 

 overthrown the theory held ever since the time of Borelli, 

 concerning the mechanism of swimming, but they have ap- 

 proached the question in another manner, that of the synthetic 



