230 INTERACTION OF NATURAL FORCES. 



the rivers, the woods, and the living beings around us. While 

 regarding the laws which have been deduced from the physi- 

 cal 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 immeasurably distant double stars 

 which are governed by exactly the same laws as those sub- 

 sisting 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 meteoric stones which sometimes fall from ex- 

 ternal 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 

 household of the universe with respect to the store of force, 

 capable of action, which it possesses. 



A number of singular peculiarities in the structure of our 

 planetary system indicate that it was once a connected mass 

 with a uniform motion of rotation. Without such an assump- 

 tion, it is impossible to explain why all the planets move in the 

 same direction round the sun, why they all rotate in the same 

 direction round their axes, why the planes of their orbits, and 

 those of their satellites and rings all nearly coincide, why all 

 their orbits differ but little from circles, and much besides. 

 From these remaining indications of a former state, astrono- 

 mers have shaped an hypothesis regarding the formation of 

 our planetary system, which, although from the nature of the 

 case it must ever remain an hypothesis, still in its special 

 traits is so well supported by analogy, that it certainly de- 

 serves our attention. It was Kant, who, feeling great inter- 

 est in the physical description of the earth and the planetary 



