6 MOVEMENT 



the hand being released, the opposing force brings the 

 first lever back into its original position, the air 

 returns from the second into the first tambour, and 

 the lever of the second falls in consequence. Thus 

 the movements produced by raising or lowering the 

 hand are transmitted after an inappreciable delay (i.e. 

 that of sound) to a lever which can record them on 

 a revolving cylinder which has been covered with 

 paper. Now, the record can be written in two ways : 

 either according to the Morse Code, by making or 

 breaking the contact between the pen and the surface 

 of the cylinder, or else in the form of a continuous 

 curve, the variations of which express the different 

 phases of the movement.* 



Chronographic Record of the Foot in Walking, as it 

 touches and leaves the Ground. — A cylinder which 

 turns at a uniform rate is covered with a sheet of 

 paper, while the points of two tracing needles, which 

 are placed side by side, touch the surface of the 



I cylinder, one of them 



| at the moment the 



a r right foot, and the 



%*. \\ °t ner a t the moment 



i. ■ - ..^■a^drel^^ V\ tlif left foot readies 



m ^^^^^^^^WJ the ground. The ob- 



^1 -^-^-s-^. .. :. "?^j ^^ ment is that each 



Fig. 3— Shoe for indicating when a man's foot needle shall COme in 



conies in contact with the ground; a transmit- . . . 



ting tube effects a communication between the COlltact With the SUr- 



air chamber and the chroiiographic tambour. - „ , 



face ot the paper as 

 the corresponding foot touches the ground. The trans- 

 mission is effected by means of pneumatic tubes. 



A particular kind of shoe (Fig. 3) is fitted to the foot 

 of the pedestrian, and the sole is composed of a thick 



* For the different applications of this sort of written record see 

 " The Graphic Method," p. 426. 



