MAREY 



21 



Marey's sphygmograph was not the first instru- 

 ment of its kind. There had been, before it, 

 Herisson's sphygmometer, Ludwig's kymographion, 

 and the sphygmographs of Volckmann, King, and 

 Vierordt. But, if one compares a Vierordt tracing 

 with a Marey tracing, it will be plain that Marey's 

 results were far advanced beyond the useless 

 1 ' oscillations isochrones " recorded by Vierordt's 

 instrument. 



Beside this improved sphygmograph, Chauveau 

 and Marey also invented the cardiograph, for the 

 observation of the blood-pressure within the cavities 

 of the heart. Their cardiograph was a set of very 

 delicate elastic tambours, resting on the heart, or 

 passed through fine tubes into the cavities of the 

 heart, # and communicating impulses to levers with 

 writing-points. These writing-points, touching a 

 revolving cylinder, recorded the variations of the 

 endocardial pressure, and the duration of the 

 auricular and ventricular contractions. 



It is impossible here to describe the subsequent 

 study of those more abstruse problems that the 

 older physiologists had not so much as thought of : 



* " On peut s'assurer de l'innocuite de ce premier temps de 

 l'experience en examinant l'animal, qui n'est nullement trouble, 

 qui marche et mange comme de coutume. En comptant le 

 chiffre du pouls, ou trouve quelquefois une legere acceleration, 

 surtout dans les premiers instants ; mais les mouvements du 

 cceur sont toujours reguliers, et donnent, a l'auscultation, des 

 bruits d'un caractere normal." (Marey, foe. cit. p. 63.) 



