RECORDING LSOPHACHAL CONTRA' TIONS 



137 



magnet which records five or ten second intervals. If a 

 metronome or Harvard clock is used, shorter time inter- 

 vals must be employed. This may call for a faster drum 

 spe<-<l. The rate should, however, be fairly slow. When 



Elastic rubber 

 band to attach 



cot fa 

 catheter 



Fig. 128. Arrangement of apparatus for recording esophageal contractions. 



all adjustments are made start the drum and record one 

 or two inches of normal tracing-. Then with a medium 

 strength tetanizing current stimulate the right vamis nerve 

 for one-half second. Wait till the records all return to 



