Etienne-Jules Marey: measuring the living

Etienne-Jules Marey (1830-1904), a physiologist and precursor of the cinema, invented some improved apparatus for measuring life processes and wrote a thesis on the circulation of the blood.His sphygmograph uses a sensor to measure arterial blood pressure. He also invented a cardiograph, the ancestor of the electrocardiogram which measures heart rhythms. Athletic effort can be measured via the variation and strength of the signal. The principles underlying these measurements have remained the same since Marey's time, the only difference being that measurement of the consumption of dioxygen is now included.