THE ORIGIN AND DEVELOPMENT OF THE EARTH a) 
FIGURE 9. 
Diagram by F. R. Moulton showing the supposed manner in which 
orbits and the spiral form of the nebula were formed. S is the ancestral 
sun of the solar system; the approaching sun passes along the path of 
the larger curve. When it is at the position S1 it draws a body at P’ 
toward it in the direction of C’. As it passes on to S2 it acts similarly 
on the particles coming out towards P. The result is a loosely coiled 
spiral, with the particles composing it revolving around the central 
mass or sun. From Chamberlin. 
