MEASUREMENTS 



283 



Marey also used another contrivance. The air vessel, containing 

 a brass spring, is placed inside the heel of an ordinary shoe. 

 A tongue of steel forming the sole is introduced under the foot 

 of the subject and rests on projecting button which works the 

 membrane of the apparatus. The pressure of the foot sends 

 a certain amount of air through an indiarubber tube, which 

 goes up behind the heel (fig. 181). This arrangement is especially 

 adapted to the study of walking. Tatin (1843-1913) devised 

 a " bellows " sole, which can be adapted to the footwear, and 

 is of an extremely simple construction. 



Marey used a dynamographic stage, or gangway, to study 

 locomotion ( 269). 



Fio 181 



Recording sole. 



213. Tools provided with Recording Devices. Professor 

 Imbert (*) applied Marey 's system of 

 registration to a tool much in use in 

 the Midi, namely, the pruning shears, 

 which are used to cut the long vine 

 shoots into slips of a variable thick- 

 ness. They are in the form of scissors, 

 that is to say, a lever of the first order 

 (fig. 182 and see 51), the fulcrum being 

 at the joint ; consequently, the effort 

 will be all the greater the further away 

 from the joint the vine-shoot is cut. 



The measurement of this effort, 

 therefore necessitates the choice of a 

 constant position for the vine-shoot 

 relatively to the tool. This is how Prof. 

 Imbert proceeded. The handle, MN, 

 of the pruning shears is cut at S, and 

 the two parts are joined by means of 

 a hinge which allows the portion SN to 

 turn round the axis O, thereby drawing 



( x ) A. Imbert (Revue d'Hygiene et de Police Sanitaive vol. xxxi. No. 8, 

 1909 ; separate reprint p. 18 ; Revue d' Economic Politique 1909 ; Revue 

 Generate des Sciences 1911, p. 481). 



182, 

 Pruning Shears. 



