4 | min and measuring the time for the skin fold to retract to the surrounding skin surface. The exact end point was sometimesdifficult to measure in older people, and if the fold had not retracted completely in 90 sec, this time measurement was used at the maximum. (3) Graying of the Hair. The degree of graying was expressed on a 0 to 4+ scale as follows: 0, no graying; 1+, slight “salt and pepper” graying; 2+, moderate ‘‘salt and pepper” graying; 3+, nearly complete graying; 4+, complete graying. Special Senses.* (1) Eyes. All ophthalmologi- cal values were obtained during the 1964 survey. (ay Accommodation was measured in diopters by use of the Prince refracting rule. The average reading ol the two eves was used. (b) Visual acuity was measured by Snellen’s test. It was found that by taking the square root of the average visual acuity (denominator) of the two eyes the scale was more linear. Thus the best vision, 20/10, was represented as 32 (the square root of 10), the worst reading, 20 ‘200, was represented as !4.1 (the square root of 200), and intermediate readings were similarly recorded. (c) Arcus senilty was esu- mated on a 0 to 44 scale. Only slight limbic clouding was considered as | + with increasing clouding as 2+ or 3+ and marked clouding as ++. (2) Fars ( flearme). Audiometric examinations wee carried out in a special cubicle lined with acoustic lle. A rugged screening type of audiomcter was used.** Impairment of hearing wasaveraged for the twoears as follows: the decibel loss for cach of the 6 frequencies (200, 500, 1000, 2000, 4000, 7000) for each ear was averaged, and a ncan frequencyloss in decibels for the two ears was obtained. Cardiovascular Changes. Systolic Blond Pressure. Two readings were obtained with the standard acronaid cufl-type sphygmomanometer, and the average of the two was used. There was no basic or "With regard to the rehabuity of determinations using the Proace cetracting cule, Snellen s test. and hearing acuity, at should be paimted out that these tests were carned out under standardized conditions, but. in view of the necessity ot using an interprercr vader teld coudigons, owas not feasible to have the test repeated bs more than one examiner “The data trom these tests ate beheved to be sutfigently, reproducible to be of relative Vatue aithough not so accure'. perhaps as might be obtained cinder mare dessrable cane. dons °° The authors are gratetul to the Armed Services Medical Provarrement Avenes, Fort Totten, New York, for loan of the audiometer Figure 33. Marshallese subject taking light-extinguishing test of neuromuscular and mental ability as part of the aging study. adjusted level of physical activity such as resting for a standard period oftime prior to the readings. Pressures were taken from the left arm with the subject supine during the course of the physical examination. Neurological and Neuromuscular Function. (1) Vibretory Sense. Vibratory perception was measured over the head ofthe left tibia by an electric vibrometer set at a standard frequency of !20/sec at 20 V. The end point was the voltage intensity required for perception o! the vibration. (2) Veuromuscular Function. This was measured by having the subject depress the key of a hand-tally type of blood cell counter as many timesas possible in the period of one minute (1964 data). The total num- ber of depressions represented the score. (3) Light Extinction Time.* A battery of lights were connected in random series, and the subject extinguished “Weare yratefulto Dr. J.W. Hollingsworth of Yale University for information on the construction and use of this instrument