200 Mr. G. J. Burch. On the Interpretation of [Feb. 11, 



on the left side, suddenly increases at a certain point from 3 to 5 units. 

 Regarded as a wave of electrical activity, this sudden change is 

 equivalent, as the right side of the figure shows, to a gradual increase 

 of wave-length to a new constant value. 



Fig. 4. — A sudden definite increase of 

 duration (left side) implies a grad- 

 ual transition from a constant short 

 wave to a constant long ware (right 

 side). 



Fig. 5. — A sudden definite diminution 

 of duration (left side) corresponds 

 to a separation of the wave of ac- 

 tivity for a short time into two 

 portions (right side). 



Fig. 5 is the converse of fig. 4, the duration suddenly diminishing 

 at a certain point from 5 to 3. This diagram brings out the curious 

 result that under these conditions the wave may split up into two por- 

 tions. Moreover, for certain positions of the leads, the record in such 

 a case would be monophasic. 



Figs. 6 and 7 show the effects of a change in the rate of propagation, 

 unaccompanied by any change in the duration. Two things should be 

 noticed — first, that the slower rate of propagation corresponds to a 



Fig. 6. — A sudden definite increase in 

 velocity of propagation, the dura- 

 tion remaining constant (left side), 

 involves a gradual increase of wave- 

 length from one fixed value to 

 another (right side). 



Fig. 7. — A sudden definite decrease in 

 velocity of propagation, the dura- 

 tion remaining constant (left side), 

 involves a gradual shortening of 

 the wave from one fixed length to 

 another. 



shorter wave unless the duration is increased in the same proportion, 

 and farther, that whereas the change of rate is sudden, the change of 



wave-length is gradual. 



