152 HISTORY OF 



with great ardour, and much has been written on 

 both sides ; and yet, when we come to examine 

 the debate, it will probably terminate in this ques- 

 tion, whether cold or heat first began their opera- 

 tions upon water ? This is a fact of very little 

 importance, if known ; and what is more, it is a 

 fact we can never know. 



Indeed, if we examine into the operations of 

 cold and heat upon water, we shall find that they 

 produce somewhat similar effects. Water dilates 

 in its bulk, by heat, to a very considerable de- 

 gree ; and what is more extraordinary, it is like- 

 wise dilated by cold in the same manner. 



If water be placed over a fire, it grows gradu- 

 ally larger in bulk, as it becomes hot, until it be- 

 gins to boil ; after which no art can either in- 

 crease its bulk, or its heat. By increasing the 

 fire, indeed, it may be more quickly evaporated 

 away ; but its heat and its bulk still continue the 

 same. By the expanding of this fluid by heat, 

 philosophers have found a way to determine the 

 warmth or the coldness of other bodies ; for if 

 put into a glass tube, by its swelling and rising 

 it shows the quantity of heat in the body to 

 which it is applied ; and by its contracting and 

 sinking, it shows the absence of the same. In- 

 stead of using water in this instrument, which 

 is called a thermometer, they now make use of 

 spirit of wine, which is not apt to freeze, and 

 which is endued even with a greater expansion 

 by heat than water. The instrument consists of 

 nothing more than a hollow ball of glass, with a 

 long tube growing out of it. This being partly 



