LEAD I 



LEADII 



c. 



DffXtfocsrr 



0123 



Fig. 84. A. Schema to illustrate method of determining the electrical axis, and to show 

 its projection on to the three leads. The direction of EG should also be shown by an arrow 

 pointing toward the right in the diagram. 



B. Diagram showing direction of spread of excitation wave in the heart, and the relations 

 of electrical axis to the three leads at different instants. (Modified from Lewis.) 



C. Curves illustrating the composite nature of the physiological electrocardiogram. The 

 two curves on the right were charted from the electrocardiograms of a monkey before and 

 after the right conducting branch had been compressed. Thi dextrocardiogram was subsequent- 

 ly calculated from these curves. Ordinates .02 millivolts. Abscissae .005 sec. (Modified from 

 Lewis, Trans. Royal. Soc., 1916, B. Vol. 207.) Below diagrams have been constructed from 

 data published by Lewis, showing rotation of the electrical axis in each chamber during the 

 production of the respective curves. 



