EXPLANATION OF DIAGRAMS. 



In the following explanation the words " lateral scale" are used to designate 

 the divisions of the background opposite the lateral battery of cameras. The 

 words "terminal scale" are used to designate the divisions of the back- 

 ground at the end of the track. 



It should also be noted that in making the study of the lateral sway, the 

 transparent scale was for convenience so applied that one of its heavy lines 

 coincided with the central line of the terminal scale. This line is in the 

 centre of the broad division occupying the middle of the background. The 

 line AB of Diagram 1 and 2 is, therefore, a projection of this line along the 

 course of the track, and the divisions and subdivisions of the scale are pro- 

 jected in relation with this central line. 



DIAGRAM 1. 



The line AB equals the length of the track. The divisions of the line CD 

 equal the divisions of the terminal background, equivalent to thirty centi- 

 metres each. B equals the position of the upright battery of cameras by 

 means of which the middle series of pictures of Plate 1 of Muybridge's pho- 

 tographs were made. EFGH equals the portion of the track on which the 

 movement photographed was made. The arrow indicates the direction in 

 Avhich the model moved. 



DIAGEAM 2. 



The portion of the track marked EFGH in Diagram 1 is in Diagram 2 

 represented much enlarged. The horizontal red lines are noticed to be of 

 two kinds, heavy and light. Of these the heavy lines represent the broad 

 divisions of the terminal scale projected along the track. They are thirty 

 centimetres apart. In the original scale this space is subdivided into six 

 others of five centimetres each. In the diagram, however, for greater ac- 

 curacy it is subdivided into ten parts of three centimetres each, as also in 

 the transparent scale used in making the actual study on the photographs. 



The vertical lines in the diagram i-epresent the vertical divisions of the 

 lateral scale projected across the track. They are, therefore, five centimetres 

 apart. 



The black and slightly converging lines constitute the corrected scale upon 

 which the measurements made on the photographs are registered and on 

 which the curves are constructed. The method by means of which this scale 

 is determined is illustrated in Diagram 1. 



The heavy black line marked f is intended to show the extent and direc- 

 tion of the lateral sway of the left foot. The lines b and d are intended to 

 show the same elements for definite points on the head and hip respectively. 



It is evident that the direction of the step was not exactly the same as that 

 of the track, but that it was slightly oblique. 



