The Duration of the After-Sensations of Warmth Aroused by Punctiform Stimulation

Abstract

Except for the modifications necessitated by the substitution of warm stimuli for cold and improvements in the device for timing the duration of the after-sensation, the apparatus and procedure used in this study were the same as those employed by Hall and Dallenbach. Stimulator. A Cornell esthesiometer was used as the stimulator.3 It was warmed by a stream of water flowing through it by the pressure of gravity. A reservoir (a gallon thermos jug) of warm water was placed high upon an adjustable rack. Employing the principle of Mariotte's bottles,4 water was siphoned from this reservoir, through the esthesiometer, and on into the top of a terminal container (see Fig. 1). Thus for given positions of the reservoir and the terminal container, the flow of water through the esthesiometer was constant despite the decreasing head of water in the system. A change in the elevation of either jug altered the rate of flow. The stimulus-temperature desired in this study was 40?C. This value was selected because it is adequate to intense warmth but not to paradoxical cold or to heat.5 To obtain this temperature, the water in the reservoir had to be about 49?C. because there was a heat loss in the tubing between the reservoir and the esthesiometer of approximately 8.4?C.