10. The Electrocardiograph
This machine doesn’t look intimidating, except for the man sticking his arms and one foot in buckets of water that are connected to electrical wires. That’s worrisome. But to fully describe how this machine functions, one must backtrack to 1843. Thanks to Italian physician Luigi Galvani, scientists knew the heart emitted electrical activity. What scientists didn’t know, was how to measure and record this activity. So they struggled, until British physiologist Augustus Desiré Waller, who used a device called a Lippmann capillary electrometer, a tube filled with mercury (which conducts electricity). If an electrical current generated by a patient’s heart was applied to the tube, it caused surface tension in the column of mercury to shift. Now a microscope could be used to observe the changes. It was a slow and rather imprecise way to measure the heart’s electrical impulses, but it intrigued Willem Einthoven, who invented the electrocardiograph in 1903.
Einthoven’s first step was to make Waller’s results a bit more specific. The results had recorded four distinct points of electrical activity in the heart, and these points were labeled A, B, C, and D. Then he got to work developing a mathematical formula the margin of error that was part and parcel of the displacement curve in the mercury column and developed a more sensitive reading that revealed five points of electrical activity, which he labeled P, Q, R, S, and T. This has proven extremely accurate and it’s still used to describe advanced readings of the heart today.