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Physiology. — "Analysis of tlie curves obtained ivith the string 

 galvanometer. Mass and tension of the quartz ivire and resist- 

 ance to the motion of the string.'' By Prof. W. Einthoven. 

 (Sequel to formei* communications on the string galvanometer). 



(Communicated in the meeling of April 22, 1905). 

 CONTENTS. 



1. Introduction. 



2. The principles of the method. 



3. The mass of the string. 



4. The resistance to the motion of the string. 



5. The acceleration. 



6. Analysis of some curves. 



7. Absolute measurements of the mass of the string and of the 

 resistance to its motion. 



8. The tension of the quartz wire. 



9. The practicability of the galvanometer for special purposes. 



1. Introduction. 



When recording the movements of the quartz wire in the string 

 galvanometer with the object of becoming acquainted with various 

 irregular oscillations of electric tension or current, we may in 

 many cases see in the directly recorded curve an accurate or 

 nearly accurate image of the oscillations sought. These cases are 

 met with if the de\'iations of the quartz wire are aperiodic and 

 quicker than the oscillations to be recorded. As an instance we 

 mention here the galvanometric tracing of the human electrocardio- 

 gram, the various tops of which are reproduced in the exact pro- 

 portions by the recorded curve, as was shown on a former occasion^). 



When very rapid oscillations are to be recorded, it is necessary 

 to make the deflections of the galvanometer also of very short 

 duration, which can easily be done by giving a great tension to the 

 string. In doing this, the movements of the string must in some 

 way be damped, however, in order to avoid oscillations. The condenser 

 method can render good service here ^), especially if it is applied in 

 such a way that the motion of the string is nearly brought to the 

 limit of aperiodicity. 



1) Vide: these «Proceedings" 6, p. 107, 1903. 



2) Vide: these "Proceedings" 7, p. 315, 1904. 



