Glass negative of electrocardiograph trace, 1915-1925
Electrocardiograms are visual representations of heart activity. They are known as ECGs. They were recorded photographically until the 1950s. This is an early glass plate negative showing the electrical activity of the heart. It was produced in conjunction with a machine called a galvanometer. A galvanometer measures small electric currents such as the heart beat. Electrodes placed on the body pick up minute electrical impulses. These cause a string within the galvanometer to move. Movement was then recorded photographically to make the electrocardiogram. Physicians examine the records for irregularities that may be a sign of disease.
Related Themes and Topics
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used to record the electrical activity of the heart
The study of diseases affecting the heart and blood vessels.