The elements of the science of nutrition / by Graham Lusk.

  • Graham Lusk
Date:
1917
Catalogue details

Licence: In copyright

Credit: The elements of the science of nutrition / by Graham Lusk. Source: Wellcome Collection.

    160/850 (page 160)
    gm. per hour and the rectal temperature rose from 37.3° to 38.3°, the ill-conducting adipose tissue preventing the heat loss. The basal metabolism was not measured in this individual, but in two additional male subjects the metabolism increased 4 and 11 per cent, as the result of exposure to hot blasts of air. The skin temperatures which were normally 30° to 350 rose to between 350 and 410 in various parts of the body. It seems remarkable that the furnishing of hot blood to the subcutaneous area had so slight an effect on the basal metabolism as compared with that of a man normally situated in whom the skin is much cooler. The effect of wind is such that an imperceptible air current may have a very pronounced influence. Rubner1 has shown that wind becomes perceptible when it attains a velocity of 0.4 to 0.5 meter a second, and that if a wind much below this thfcshold value, having a velocity of 0.18 meter per second, act upon the exposed area of the arm, there is an increased heat loss of between 19 and 75 per cent., depending on the temperature of the wind, above what would be lost were the air quiet. The effect of wind of moderate humidity and different tempera- tures on the metabolism of a man clad in summer clothes, as com- pared with the metabolism during atmospheric calm, is shown in Wolpert’s2 experiment below: INFLUENCE OF WIND ON METABOLISM IN MAN Temperature Calm Wind x Meter per Second Wind 8 Meters per Second Grams CO2 per Hour Grams CO2 per Hour Grams CO2 per Hour 2° 29.8 10-15° 25.1 28.3 30.0 I^-20° 24.1 .... 30.1 20-25° 25.0 .... 28.0 25-30° 25-3 22.2 24.4 3°-35° 23-7 .... 21.0 35-40° 21.2 22.2 22.1 According to this, a breeze having a temperature of 150 to 20° and moving at the rate of about 15 miles per hour (8 meters per second) has a greater effect upon the metabolism of a man clad in 1 Rubner, M.: Arch. f. Hyg., 1904, 50, 296. 2 Wolpert, H.: Ibid., 1898, 33, 206.