THE OUTGO OF ENERGY 



finger of the other hand in the beaker at 45. 

 After 45 seconds place both fingers in the water 

 at 10. 



The finger taken from the water at 32 (which 

 is about the normal temperature of the hand) will 

 feel colder than the other fingsr. Extreme tem- 

 peratures of heat or cold fatigue the temperature 

 spots. 



Relation of Stimulated Area to Sensation. In- 

 sert a finger of one hand in a beaker of warm or 

 cold water. Note the sensation. Insert a finger 

 of the other hand in the water. 



The intensity of the sensation will increase 

 with the extent of the surfaca stimulated. 



Perception of Difference. Provide two beakers 

 of water, one-at 30, the other slightly warmer or 

 colder. By introducing a finger first into the one 

 and then into the other, and varying the tem- 

 perature of the water, ascertain how small a 

 difference in temperature can be detected. 



Usually a difference of 0.5 C. is easily recog- 

 nized. 



Relatively Insensitive Regions. 1. Compare 

 the temperature sensation perceived on touching 

 with a pencil point the median line of the fore- 

 hsad, nose, and chin with that perceived on 

 touching the skin on either side of the median 

 line. 



