In 1855, Karl Vierordt invented the sphygmograph, the ancestor of the blood pressure device and first of many devices that estimated blood pressure indirectly. The main purpose of a sphygmograph was to reproduce a pulse wave in a visual format. The medical world had not yet realized the importance of blood pressure measurement and the Vierordt sphygmograph was viewed more as a research instrument than a clinical one. The Vierordt sphygmograph is unfortunately lost and all that exists today are depictions of the device in various history books.
I have recently purchased an outstanding device, the 1886 Von Recklinghausen Tonometer, manufactured by J&A Bosch in Strasbourg. This tonometer is an extraordinary feat of engineering and medical precision and is the direct evolution of Vierordt's idea, put in practice by Von Recklinghausen. It goes to show that there are in fact very few evolutions, and that by definition most, if not all, innovations are in fact natural evolutions of previous technologies.
The only way to predict the future is to understand the past...
Von Recklinghausen was particularly important as a physician and scientist, and is the man who, through a series of elegant experiments, demonstrated the direct relation the width of blood pressure cuffs and accuracy of results. Following his research, the narrow 5-cm cuffs used by Riva-Rocci in his sphygmomanometer were replaced by the 12 cm wide cuffs that have become the standard of the today.
In this gorgeous device, the variations in pressure caused by the systolic peak are transmitted through a tube to a curved blade that displays these variations on a bezel. With this tonometer, a stethoscope was not needed to listen for Korotkoff sounds, they were instead represented as oscillations of a needle. This is truly the missing link between palpation and blood pressure measurement.
Discover this, and many fine other instruments on www.bloodpressurehistory.com