THE GENESIS OF WORLDS. 73 



or imperceptible ; but it always exists, and is reclairnable back 

 again into tlie same in mode and quantity from which it started. 



The grandest exemplification of these truths will be found in 

 what we are now considering, the origin of the celestial revolu- 

 tions. The condensation of gases gives out heat in direct pro- 

 portion to the contraction of volume. The attraction of gravi- 

 tation, not only between masses but between all particles of 

 matter, increases in the inverse square 'of the diminishing dis- 

 tance. From these two principles it can be mathematically 

 shown that in the contraction of each great world-nebula, heat 

 would be set free in the precise proportion of the increase of 

 atomic attraction ; or in other words that it would take the ex- 

 act amount of heat-force that had been released, to separate the 

 atoms again to their original distance apart. But in this instance 

 the heat-force is not really set free ; it is transformed into the 

 motion of the mass from which it came. Instead of holding the 

 atoms apart, the work which it now has to do under the form of 

 motion is to prevent the masses from falling into each other. 

 It is this motion the celestial revolutions which keeps the 

 worlds apart, and allows each to work out its destiny under the 

 aggregating forces, without any interference from any other. 

 Up to a certain point of condensation, which is previous to the 

 radiation of heat into space, if this motion were at any time 

 stopped, it would be resolved into just the amount of heat 

 necessary to expand the mass again to its original dimensions. 



The attractive forces, gravity, chemical affinity, arid cohesion, 

 whether these forces are many or one, are inherent properties of 

 matter. Every atom has its definite capacity of attraction, 

 which may be exercised or not according to circumstances. For 

 it is evident that an attracting body may be at the same time 

 drawing toward itself a million other like bodies, or none at all, 

 without change of its power of attraction. In like manner 

 the magnet has a definite lifting power whether it is actually 

 holding up a weight or not. If this attribute of matter is not 

 operative, or but partially so, it is because heat, or motion, or 

 some repellent force, is holding the atoms or the masses at a dis- 

 tance from each other, and thus opposing the exercise of it. 



