84 Introduction to the Study of Science 



III. TEMPERATURE THE THERMOMETER 



37. Our feeling of temperature. Have you not observed 

 that of many individuals in a room no two may feel or judge 

 the temperature to be exactly the same? One may find it 

 too warm for comfort, another, too cold. The same individual, 

 moreover, may one day experience no discomfort in a room with 

 a given temperature, but the next day be extremely uncom- 

 fortable when the temperature is the same. Is our feeling or 

 judgment of the temperature of any external object, such as 

 water, air, wood, iron, stone, or cloth, reliable? Can you 

 judge accurately how hot or cold a body is? The following 

 experiment will demonstrate to what extent we can depend 

 upon our sensations of temperature and its changes. 



Exercise. Hold one hand in water as hot as it can be endured, 

 and the other hand in cold water, for two or three minutes. Then 

 put each hand alternately into lukewarm water. What are your 

 sensations of temperature in each case? Can you judge accurately 

 the temperature of lukewarm water in this way? Put the hand that 

 was held in cold water into the hot water, and then into the lukewarm 

 water. What are your temperature sensations at each trial? 



What do these experiences indicate as to the reliability of our feel- 

 ings of temperature and its changes? Do you imagine that an indi- 

 vidual in a fever can feel or judge the temperature of a room cor- 

 rectly? Explain. What do you infer from this as to the relation of 

 our bodily condition to sensations of temperature of external things? 



It is interesting to note how we get sensations of heat and cold. 

 It may be imagined that we feel heat and cold equally over all the 

 skin. With a cold nail having a sharp point or a lead pencil touch 

 different places on the back of your hand. Do all places give sen- 

 sations of cold? Mark such as do with black ink. With the point 

 of the nail warmed, find spots that give a feeling of warmth and mark 

 them with red ink. Do the cold and warm spots coincide? Apply 

 the warmed nail point to a spot which is marked black as designating 

 a cold spot. What is the result? Try a cold point upon a warm 

 spot. Are the spots well distributed over the back of your hand? 

 Do they merge into each other or are they quite distinct? The tem- 

 perature spots, as they are named, are distributed more or less sparsely 

 over the whole body. 



