ox THE INTERACTION OF NATURAL FORCES. 173 



mula, which only speaks of the heat, volume, and pressure 

 of bodies, was able to discern consequences which threat- 

 ened the universe, though certainly after an infinite period 

 of time, with eternal death. 



I have already given you notice that our path lay 

 through a thorny and unrefreshing field of mathematico- 

 meclianical developments. We have now left this portion 

 of our road behind us. The general principle which I 

 have sought to lay before you has conducted us to a point 

 from which our view is a wide one ; and aided by this 

 principle, we can now at pleasure regard this or the other 

 side of the surrounding world according as our interest 

 in the matter leads us. A glance into the narrow labora- 

 tory of the physicist, with its small appliances and com- 

 plicated abstractions, will not be so attractive as a glance 

 at the wide heaven above us, the clouds, the rivers, the 

 woods, and the living beings around us. While regarding 

 the laws which have been deduced from the physical 

 processes of terrestrial bodies as applicable also to the 

 heavenly bodies, let me remind you that the same force 

 which, acting at the earth's surface, we call gravity 

 {Schwere\ acts as gravitation in the celestial spaces, and 

 also manifests its power in the motion of the immeasu- 

 rably distant double stars, which are governed by exactly 

 the same laws as those subsisting between the earth and 

 moon ; that therefore the light and heat of terrestrial 

 bodies do not in any way differ essentially from those of 

 the sun or of the most distant fixed star ; that the me- 

 teoric stones which sometimes fall from external space 

 upon the earth are composed of exactly the same simple 

 chemical substances as those with which we are acquainted. 

 We need, therefore, feel no scruple in granting that general 

 laws to which all terrestrial natural processes are subject 

 are also valid for other bodies than the earth. We will, 

 therefore, make use of our law to glance over the house- 



