AND THEORY OF THE HEAVENS. 77 



particles scattered throughout the whole region will fall 

 to that point. The first effect of this general fall is the 

 formation of a body at this centre of attraction which, so 

 to speak, grows from an infinitely small nucleus by rapid 

 strides ; and in the proportion in which this mass in- 

 creases, it also draws with greater force the surrounding 

 particles to unite with it. When the mass of this central 

 body has grown so great that the velocity with which it 

 draws the particles to itself from great distances, is bent 

 sideways by the feeble degrees of repulsion with which 

 they impede each other, and when it issues in lateral 

 movements which are capable by means of the centrifugal 

 force of encompassing the central body in an orbit, then 

 there are produced whirls or vortices of particles, each 

 of which by itself describes a curved line by the com- 

 position of the attracting force and the force of revolution 

 that has been bent sideways. These kinds of orbits all 

 intersect each other, for which their great dispersion in 

 this space gives place. Yet these movements are in 

 many ways in conflict with each other, and they 

 naturally tend to bring one another to a uniformity, that 

 is, into a state in which one movement is as little 

 obstructive to the other as possible. This happens in 

 two ways : first, by the particles limiting each other's 

 movement till they all advance in one direction; and 

 secondly, in this way, that the particles limit their 

 vertical movements in virtue of which they are approach- 

 ing the centre of attraction, till they all moving 

 horizontally, i.e. in parallel circles round the sun as their 

 centre, no longer intersect each other, and by the centri- 

 fugal force becoming equal with the falling force they 

 keep themselves constantly in free circular orbits at the 



