20 MODERN SCIENCE : 



Jsdo you mean jj/ 3 or do you mean /eels, appears? Cold in what 

 sense ? Cold to yourself, or^to other people, or to polar bears, or by the 

 thermometer ? And so on. Science therefore steps in with an air of 

 authority and sets him right. It says the temperature is jo degrees Fahren- 

 heit, as if to settle the matter. But does this really settle the matter ? 

 Temperature who knows what that is? What is the scientific definition 

 of it? I find (Clerk-Maxwell's Theory of Heat, p. 2.) "the temperature 

 of a body is a quantity which indicates how hot or how cold the body 

 is." This sounds very mnch like saying, "The color of a body is a 

 quantity which indicates how blue, red, or yellow the body is." It does 

 not bring us much farther on our way. But in the next paragraph 

 Maxwell shows the object of his definition (which of course is only pre- 

 liminary) by saying, " By the use, therefore, of the word temperature, we 

 fix in our minds the conviction that it is possible not only to feel, but to 

 measure, how hot a body is." That is to say he clearly maintains that it 

 is possible to find an absolute standard of hotness or coldness or rather 

 of the unknown thing called temperature outside of ourselves and inde- 

 pendent of human sensation. When the man said he was cold he was 

 probably just describing his own sensations, but here Science indicates 

 that it is in search of something which has an independent existence of 

 its own, and which therefore when found we can measure exactly and 

 once for all. What then is that thing? What is temperature? say, what 

 is it ? 



We cudgel our brains in vain. Perhaps the remainder of the sentence 

 will help us. "The temperature is 30 degrees Fahrenheit." "The un- 

 known thing is thirty degrees." When then is a degree? That is the 

 next question. When the Theory of Heat went out from sensation and 

 left it hehind, one of its first landing places was in the expansion of 

 liquids as in thermometer tubes. Here for some time was thought to 

 be a satisfactory register of "temperature." But before long it became 

 apparent that the degree Fahrenheit, Reaumur, or what-not was an 

 entirely arbitrary thing, also that it was not the same l thing at one end of 

 the scale as the other, and finally that the scale itself had no starting 

 point ! This was awkward, so a move was made to the air thermometer, 

 and there was some talk about an absolute zero and absolute tempera- 

 tures ; it was thought that the Unknown thing showed itself most clearly 

 and simply in the expansion of air and other gases, and that the "degree" 

 might fairly be measured in terms of this expansion. But in a little time 

 this kind of thermometer chiefly because no gas turned out to be " the- 

 oretically perfect " broke down, absolute zero and all, and another step 

 had to a made namely, to the dynamical theory. It was announced 

 that the Unknown thing might be measured in terms of mechanical energy 



i The very fact alone that the degrees on a thermometer are equal space divisions 

 shows that they must bear a varying relation to the total volume of liquid as that expands 

 from one end of the tube to the other. 



