quently a heart murmur is accidently discovered. In my experience it is equally common, in persons past middle life, to discover a wholly unexpected high blood pressure.

A blood pressure reading of more than 145 mm., before middle life, and of more than 160 mm. after, must be considered abnormal.

Permanent high blood pressure, in the vast majority of cases, is due to chronic nephritis, even though the urine may for long periods be normal.

(c) Examinations for certifying to a condition of health. The number of persons whose unsuspected cardiac hypertrophy and high blood pressure are first detected by the sphygmomanometer, are to me a convincing argument for the necessity of a blood pressure reading, before certifying to the existence of a state of health. The life insurance companies are beginning to appreciate this.

Second, in obstetrical work.

Third, in the diagnosis of acute abdominal pain. In acute infectious diseases. In nervous diseases.

Fourth, the special opportunity of the general practitioner to contribute to our scientific knowledge of the subject. The clinical study of blood pressure is still in its infancy. Of the real physiological mechanism by which permanent high blood pressure is maintained we know nothing as yet. Of the clinical history of high blood pressure in the individual we know far too little. I am convinced that we shall never begin to realize the diagnostic possibilities of clinical sphygmomanometry, until all of us who practice medicine learn to record the blood pressure of all our patients from time to time, beginning when they are young and well. Then we shall know definitely their individual level of pressure during health and detect early variations from it."

The sphygmomanometer was first perfected and adopted to clinical purposes by Professor V. Basch, of Vienna, in 1876, and modified by Potain in 1889. It was not until 1896 that an instrument was devised which permitted a practical and accurate estimation of arterial pressure. At about the same time, 1896, Riva Rocci, working in Italy, and Hill in England,

devised a simple and practical instrument. The air system, the constricting band, and the manometer of the Riva Rocci instrument are familiar to all, and appear more or less modified, as the essentials in all sphygmomanometers now in general use. In the use of any instrument we should see that the constricting band is at least 10 c.m. or 4 inches wide; that it is applied snugly well above the elbow joint. Roger's sphygmomanmeter reverts to the type represented by the late models of V. Basch and Potain, in that a metallic indicator is substituted for the mercury column manometer. The result is an extremely compact and portable apparatus, which when folded in its case can be carried in the coat pocket.

In determining the systolic pressure, the level of the mercury column at the instant that the pulse passes the compression band will represent the systolic pressure in the vessel under observation. The diastolic pressure may be obtained in several ways. The method of observing the greatest excusion of the mercury in its gradual fall after taking the systolic pressure is too uncertain for practical use. The auscultatory method, first suggested by Sterzing, has been advocated recently by Goodman of Philadelphia, and is the only accurate means of determining the diastolic pressure. The method is as follows: After applying the apparatus in the usual manner and having raised the pressure to obliteration of the pulse, a stethoscope is placed over the radial artery below the cuff. As the pressure is gradually allowed to fall, a sharp thump is heard as the circulation commences. This represents systolic pressure. This tone now undergoes a number of changes, until it suddenly becomes very faint and almost immediately disappears. The reading of the sphygmomanometer at this moment represents the diastolic pressure.

The systolic pressure, as indicated by the sphygmomanometer, represents the pressure within a vessel at the time of systole of the ventricles.

The diastolic pressure represents the ebb to which the arterial pressure falls during cardiac diastole.

The pulse pressure is the difference between the systolic

and diastolic pressure. The normal pulse pressure ranges between twenty-five and forty millimeters.

The factors that enter into the productions of blood pressure are (1) the contraction of the ventricles, (2) the resistence offered by the arteries and arterioles by virtue of their normal elasticity, which is known as vasomoter tone and (3) the volume of blood in the vascular system. It is evident that during systole, blood pressure is the resultant of two forces, ventricular contraction and peripheral (arterial) resistancethe third factor, the volume of the circulating blood, may be disregarded under ordiary conditions-while during diastole the ventricle is passive, and the periperal resistance alone comes into play. It is necessary, therefore, in studying arterial tension and pulse pressure to determine both the systolic and diastolic pressure.

From a large number of observations by observers upon the normal human adult, it has been determied that the normal systolic blood pressure may vary between 110 and 145 m.m. Hg. the normal pressure for women being from 8 to 10 m.m. less.

In children under two years of age Cook places the normal systolic pressure between 75 and 90 m.m. According to Lauder Brunton the maximum pressure in children between 8 and 14 years is 90 m.m. Hg. in youths from 15 to 21 years, from 100 to 120 m.m.

Faucht gives a convenient rule for estimating the normal blood pressure at different ages, which coincides with the experience of most observers. Taking 120 m.m. as the normal at the age of twenty, he adds 1⁄2 m.m. for each additional year; thus at age of forty 130 m.m., age of fifty 135 m.m., age of sixty 140 m.m.

ARTERIAL HYPERTENSION.

Among conditions in which hypertension is a prominent feature may be mentioned diseases of kidneys, especially chronic interstitial nephritis; chronic autointoxication due to faulty metabolism, not necessarily associated with kidney lesions, gout and lithemic diathesis; arterio-sclerosis; lead poisoning, emphysema and chronic bronchitis, certain forms

of valvular heart disease, especially aortic regurgitation. The cause of hypertension which is probably the most widespread and the most frequent is intoxication. It is generally considered that it is the irritation from poisons retained by the kidneys and not the mechanical obstruction which sends the blood pressure up in nephritis.

With regard to arterio-sclerosis, it is well known that, while hypertension is the rule, the opposite condition is often observed, depending on the condition of the heart muscle. Late in the disease, when myocarditis has resulted from insufficient nutrition of the myocardium, the blood pressure may be reduced. Owing to the hardening of the vessel wall, it is impossible to obtain a correct idea of arterial tension in arteriosclerotic patients without the sphygomomanometer. It is very probable that all cases of arterio-sclerosis go through a preliminary stage of vascular spasm and hypertension before actual changes take place in the coats of the vessels, and it is during this so-called prearterio-sclerotic stage that the therapeutic indication to be derived from the systematic blood pressure observations is most valuable.

Clinical experience has demonstrated that the conditions of arterio-sclerosis and chronic interstitial nephritis are with difficulty treated as separate and distinct conditions. Their corelation is so frequent that we have come to look upon contracted kidney of chronic interstitial nephritis as but the terminal stage in arterio-sclerosis. An increase in blood pressure produces arterio-sclerosis, causes rupture of a diseased artery, apoplexy; overtaxes the heart, myocarditis; accompanies or in some cases apparently causes renal insufficiency, nephritis.

Dr. Cook, in an article on Blood Pressure in Prognosis, says: "The Mutual Life Insurance Company's statistics of deaths from 1843 to 1898 show about 30 per cent. due directly to cardiovascular renal disease. When we consider the part that this factor plays as the primary cause in pneumonia, bronchitis, pulmonary edema, etc. (72 per cent. of deaths from respiratory diseases were over forty-five years of age), to ascribe one-half of all deaths directly or indirectly to this

group would probably not be an overestimate. The U. S. Census Report for 1908 gives about 25 per cent. of total deaths due directly to cardio-vascular renal disease, and this total, of course, includes the large mortality in infancy and childhood."

The treatment of arterial hypertension is chiefly hygienic and dietary, and may be summed up as moderation in all things. It should include the regulation or interdiction of poisons, which increase blood pressure or damage the myocardium, of which tobacco is especially important; the regulation of the whole mode of life so as to prevent undue excitement, worry or nervous strain, and sudden or excessive exertion, which are definitely bad for these patients; the insistence on moderate exercise proportionate to the strength of the heart; the use of massage and baths where exercise cannot be taken; the regulation of the diet and water and salt intake.

Rosengart of Frankfurt has shown that abdominal arteriosclerosis is liable to induce annoying flatulence, painful distension, especially in the right hypochondrium. In cases of apparent appendicitis or gall stones with atypical symptoms we should hesitate to advise operative interference in the presence of tube casts and high pressure.

Uremeia is always preceded by a marked rise in pressure, and as the signs increase, so does the pressure. As in other conditions, the effect of treatment may be definitely measured by the sphygomonanometer. This is well illustrated by Dr. McClintock's notes on a case of acute nephritis that was admitted to the City Hospital on February 13, 1912. during my service. F. H., age 15 years. History of over indulgence in sweets to an excessive degree. He would also eat a dozen bananas at a time. Had frequent stomach attacks with vomiting and severe headache. On admission to the hospital he had irregular bilateral clonic convulsions with nystagmus. These were repeated again and again, becoming unilateral on left side, starting in left hand. When momentarily conscious, complained of pain in right side of head over eye. Was unconscious at first, later was delirous, very irritable and swore fiercely. Convulsions ceased February 14th at 9 a. m.