KATATHERMOMETRIC MEASUREMENTS OF INSULATING PROPERTIES OF THE FUR IN SMALL MAMMALS

Physical regulation of heat, as an adaptive character, plays an important role in the relations between an organism and its environment. The hairy covering, consti-tuting a thermo-insulating layer, is its essential factor. Various instruments have been used so far to examine the insulating properties of fur. H a m m e 1 (1955), for instance, adopted the apparatus used by the American Society for Testing Materials to examine thermal properties of fabrics for his studies on 15 mammals species. The degree of insulation for a thickness unit of a fur taken freshly off was determined by measuring the temperature gradient in this fur penetrated through by a known amount of heat coming from a heated metal disk. By means of such an instrument L e n t z & H a r t (1960) have measured the heat loss through the fur of new-born caribou. B u r t o n & E d h o l m (1957) have introduced a unit applied for determination of the insulating value of man's clothing (clo): °C 1 clo = 0.32 — 0.14 Cal./sq.m. X hrs The dependence of the cooling effect upon the insulating value is evident. As regards the furs of small mammals, it is, however, practical to use Hill's kata-thermometer, which makes it possible to obtain the ready value of cooling immediately. Hill's katathermometer is an instrument commonly used in biometeorology fo