242 



of the action of the Vagus iktvc. I'liilosopli. Trans R. S. 1882. CLXXill 9'jS - 

 1033 (p. 1017—1018) 5 pi. 



5. H. Frédériuq. PouIs allernant produit cliuz le cliien chloialisé par excitation 

 des nerfs accélérateurs du coeur. Archives internationales dePhysiologie 1912. p. 47. 



6. W. Trendelenburg. Untersuchungen iiber das Verlialten des Herzmuskels 

 bei rhythmischer electrisclier Reizung. Engelmanks Arcliiv f. Pliysiologie 1903, S. 271. 



7. H. E. Hering. Das Wesen des Herzalternans Munch. Med. Wochensclir. 

 1908 Seite 1417. 



8. K. V. Wenckebach- Die unregelraiissige Herztiiligkeit und ihre klinische 

 Bedeutung 1914 Seite 198—215. 



9. S. DE Boer. Herzalternans. Zentralblalt fur Pliysiologie. I'd. XXX, N". 4, 

 Seite 149 (15 Mei 1915). 



Physiology. — •'Upon the .simultaneous re(/i,stratio?i of electric 

 phenotnena liy means of tmo or more galvanometers, and 

 upon its application to electro-cardiography." By W. Eint- 

 HOVEN, F. L. Bekgansius, and J. Bijtel. 



(Communicated in the meeting of May 29, 1915). 



For a long time the need lias been felt of a siniultaneons regis- 

 tration of electric phenomena bv means of two, or three galvanometers. 

 This is evident from the experiments made by Hull. Garten, Hoff- 

 man, Lewis, Wilijams, and others. 



Speaking generally, three metiiods may be distinguished: 



^1. That in which two galvanometers are placed side by side. 

 Each of the instruments is iUnminated by a separate lamp, while 

 the rays which proceed from the projection-oculars form two fields 

 of illumination one beside the other on the horizontal slit, behind 

 which the photographic plate is moved in a vertical direction. 



The time-registration can be obtained by a single spoke-disc, the 

 number of spokes of which may be 10, or a multiple of ten. The 

 disc must be placed in such a position that its centre falls in the 

 line, which, running about parallel with the slit, connects the optical 

 axes of the two galvanometers. This can easily be done with great 

 accuracy, so that no greater error need occur than say 0,01 part 

 of the distance which divides one spoke from another. Care must 

 also be taken that by a suitable placing of the lenses the images 

 of the spokes on the slit are sliarply defined. 



B. Another method consists in stretching two strings across the 

 same magnetic field. The Cambridge Scientific Instrument Comp. 

 provides a double string-holder on their model of galvanometer, in 

 which two strings are held at a distance of 0.5 mm. from each other. 



