As far as we can as yet judge, the first objective symptom that points to threatening sclerosis is a more or less continuous rise of systolic pressure, as measured by the sphygmomanometer (the use of this instrument is imperative). The following extract from the _Lancet_ January 8, 1916, puts the matter very clearly: “The clinical value of observations on Blood Pressure is doubted only by those who have never made them. It is true that the finger can detect some difference in pulse tension, but it is often entirely at fault, since it can only estimate total pressure, thus missing a high pressure, if the volume be small. In the same way, although the hand can detect differences of temperature, it cannot replace the thermometer. The sphygmomanometer has enlarged our ideas, cleared up difficulties in diagnosis, and helped in prognosis. This has naturally reacted on treatment; it has enlarged our ideas on ‘heart failure.’ The heart is adjusted to work at certain pressures, and though within considerable limits it can adjust itself to variations, those limits may be exceeded.” There are subjective signs, especially in middle age, which point the same way, but we can seldom get hold of patients at this early stage. These are chiefly shortness of breath, on slight exertion, which makes a man realize that he has almost suddenly got out of condition, that the elasticity of youth has gone; a feeling of brain fatigue, quite out of proportion to the work done; sometimes giddiness and tinnitus, especially on stooping. Whether these symptoms appear before there is a rise of pressure it is difficult to say, but they should certainly in all cases suggest blood pressure testing. The key to the patient’s future then lies first in our hands, and then in his, life or death, health or disease, a full working life and happiness or incapacity and failure. The examination must be carefully made and frequently. The best time to take pressure is about two hours after food, when there has been a time of physical quiet, and no hurry or emotion. The position should be either recumbent or sitting in a chair, with the arm resting on a table (the muscles of the arm should not be in action), and the wrist should be on the same level as the heart. Pressure readings are higher when standing than sitting, and when sitting than lying down, the difference being from four to eight millimetres. In the early stages pressure varies a good deal, and will not show a rise at all times of day; in the early morning particularly it is often quite normal. The question now arises, What is the normal? For our purpose we may leave out the question of pressures in childhood and early life, and may take the following figures as a fair average for our calculation:-- From 40 years of age to 50, 130 mm. to 135 mm. 50 " " 60, 135 mm. to 145 mm. 60 " " 70, 140 mm. to 150 mm.