In the classic book The Principles and Practice of Medicine, Sir William Osler did not mention hypertension or its archaic name, hyperpiesis . He obviously could not address a disease still undiscovered at that time, when the available noninvasive method to measure blood pressure (BP)—the sphygmograph, which measured the amplifed radial pulse—was not reliable and practical for clinical use. Scipione Riva-Rocci opened up a new era, presenting the sphygmomanometer in 1896 . Pulse palpation measured only systolic BP. Nikolai Sergeyevich Korotkov, a Russian surgeon, identifed diastolic BP by auscultation in 1905 . For many decades, the only novelty in BP measurement was the misspelling of the name “Korotkov ,”which was changed to “Korotkoff” in some publications. Chapter 3 discusses the methods used for BP measurement Businesspersons were the frst people to identify the risks of high BP. In 1911, the medical director of the Northwestern Mutual Life Insurance Company determined that applicants for life insurance should have their BP measured with a sphygmomanometer . Sir William Osler, in a lecture given to the Royal College of Physicians and Surgeons of Glasgow in 1912, proposed that BP over 160 mmHg was high . He did not, however, suspect its importance in the pathogenesis of atherosclerosis.