ON THE ORIGIN OF THE PLANETAEY SYSTEM. 147 



If the path about the attracting centre is exactly 

 circular, the attracting force always acts on the 

 planets, or on the lead sphere, with equal strength. 

 In this case, it is immaterial according to what law 

 the force would increase or diminish at other dis- 

 tances from the centre in which the moving body 

 does not come. If the original impulse has not been 

 of the right strength in both cases, the paths will not 



FIG. />. 



be circular but elliptical, of the form of the curved 

 line in Fig. 5. But these ellipses lie in both cases 

 differently as regards the attracting centre. In our 

 model, the attracting force is stronger, the further the 

 lead sphere is removed from its position of equilibrium. 

 Under these circumstances, the ellipse of the path ha* 

 such a position in reference to the attracting centre,, 

 that this is in the centre, c, of the ellipse. For planets, 

 on the contrary, the attracting force is feebler the 



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