THE STETHOMETER 



207 



pulled from the tambour, which is therefore expanded. The variations in 

 volume of the tambour are then recorded by a second tambour. 



Experiment 2.— Take a tracing by Burdon-Sanderson's stethometer. 



Inst. Co. Ltd. Caui>. 



Fig. 166. — Sanderson's Stethometeu. 



Fig. 166 shows the general form of the instrument, and fig. 167 the way in 



which it is fitted to the chest for recording the changes in transverse diameter. 



It consists of a large tambour a with a central disc of metal fixed to its 



Fig. 167. 



■ Mode of Applying the Stethometeb to Record Ciiam.i - i\ 

 Transverse Diameter of the Chest. 



rubber membrane. An ivory knob, b ; , attached to one end of a BOTOX carried 

 at the end of a spring e serves for adjustment to one side of the cheat. At 



