I"' 



THE STUDY OP MUSCLE PHYSIOLOGY. 



183 



Fig. 171.— Tambonr of Marey (alter McKendrick). a, metallic case; 6, thin India-rub- 

 ber membrane; c, thin disk of aluminium supporting lever d^ a small portion of 

 which only is represented; e, screw for placing support of lever vertically over c; 

 /, metallic tube communicating with cavity of tamoonr for attachment to an In- 

 dia-rubber tube. 



tially of a rigid metallic case provided with an elastic top, to 

 which a lever is attached, the whole being brought into com- 

 munication with a column of air in an elastic tube. The work- 

 ing of such a mechanism will be evident from Figs 170 and 173. 



Fig. 172.— Tambours of Marey arranged for transmission of movement (after McKen- 

 drick). a, receiving tambour; S, India-rubber tube; c, registering tambour; /it 

 spiral of wire, owing to elasticity of which, when tension is removed from a, the 

 lever ascends. 



The greatest danger in the use of such apparatus is not fric- 

 tion but oscillation, so that it is possible that the original move- 

 ment may not be expressed alone or simply exaggerated, but 

 also complicated by additions, for which the apparatus itself is 

 responsible. 



