CusACK — Suman Locomotion. 533 



by him in the "Machine Animale " in a chapter entitled the 

 " Marche de rHomme," 



Marey had a man walking round in a circle 6 metres in diameter, 

 and pushing a beam in front of him. IN'ow it will be seen that when 

 a man walks round a circle his inside foot will not have so much 

 ground to cover as his outside foot, and also that he will have to 

 turn through a considerable angle at each step. A man would 

 walk round this circle in about 25 steps, so he would be really walk- 

 ing a polygon with 25 sides and would thus have to turn through an 

 angle of 14° each step. These facts I think would account for the 

 fact that Marey appears to get much greater variations than were got 

 in my experiments, though indeed from the very meagre account 

 given, it would be difficult to say accurately what results he got. But 

 one great difference easily perceived is that he gets the velocity 

 greatest at the commencement of each step, and gradually diminishing 

 until the end of the step, whereas from these experiments it would 

 appear as if the velocity only reached its maximum a short time after 

 the step is commenced, and reaches a minimum before the step is half 

 completed. 



A reproduction of a paperoff the chromograph isshown(fig. 2, p. 532). 

 The wavy line is that marked by the tuning-fork, each of the waves 

 representing the nineteenth of a second. The little strokes are made 

 by the electric magnet in circuit with the commutator of the cylinder, 

 which if the individual walked uniformly would be equal in length, 

 and each wave would have the same number of strokes in it. The 

 other line with an occasional "shake" in it, is that made by the 

 pedometer. "When the line after a "shake" is higher than before 

 the "shake" — during the time the line is higher, the heel of the 

 foot to which the pedometer was attached was on the ground (in the 

 present case the left foot) ; — when the heel was raised, there is another 

 " shake," and the line returns to its old position, the left heel being 

 off the ground. These papers were dipped into a weak solution of 

 shellac to preserve the smoking on them, which otherwise might be 

 rubbed off. 



