Hoover has called attention to the direct palpation of the femoral artery just below Poupart's ligament as a more accurate index of the pressure in the aorta than the palpation of the radial artery. Possibly one can obtain a more accurate estimate of the blood pressure in this way. This, however, is open to dispute. To estimate the blood pressure by palpating the radial artery is most deceptive. In about 75 per cent of cases one can tell fairly well whether the pressure is abnormally high or abnormally low. Small variations are impossible to determine. Unquestionably it is most advantageous to get into the habit of palpating the femoral artery and checking the result with the sphygmomanometer so that the fingers may be trained to appreciate as accurately as possible changes of pressure. It may be that one day when the instrument is needed it is not at hand. A well-trained touch then becomes a great asset. =Precautions When Estimating Blood Pressure= There are certain precautions which must be strictly observed when deductions are drawn from the manometer readings. The psychic factor must be reckoned with. Any emotion may cause marked variations in the pressure. Excitement and anger are especial sources of error. Even the slight excitement arising from taking the first blood pressure on a nervous patient especially is apt to give false values. Usually the readings must be taken many times at the first sitting and the first few may have to be set aside. Worry is a potent factor in raising the pressure. A walk to the physician's office, especially if rapid, has its effect. The position of the patient when the blood pressure is taken is important. Usually in the office the pressure is taken when the patient sits in a chair. He should assume a relaxed, comfortable attitude. The readings should be made at the same time of day and at the same interval between meals. The pressure in both arms should be measured and comparisons should be made only between readings on the same arm. These precautions may seem useless and even somewhat trivial, and the conditions difficult to control. But unless they are carefully observed the readings will be false, no comparisons can be drawn between the readings on different days, and the instrument will most probably be blamed. I have known this to happen so often that I can not emphasize too strongly the importance of controlling all the essential conditions which go to make accurate work. =The Value of Blood Pressure= In the past few years there has been a veritable avalanche of blood pressure instrument salesmen who have covered the country, sold instruments, and have made many startling claims for the instrument. They have emphasized its value out of proportion to what the instrument can do even in the hands of one familiar will all the defects. Consequently it is not necessary to emphasize the value of blood pressure. It seems best to utter a few words of caution in regard to its interpretation.