Other lines existed in the same sheet of matter.  One of these lines or pathways was destined for the orbit of Mercury; another for the orbit of Venus.  One was for the pathway of Mars; another for the belt of the asteroids; another for Jupiter; another for Saturn, and still two others, far off on the rim, for Uranus and Neptune.  The theory continues that such are the laws of matter that these orbital lines must exist in a disc of fire mist such as that out of which our solar universe has been produced.  The New Astronomy holds firmly to the notion that the orbits of the planets are as much a part of the system as the planets themselves, and that both orbit and planet exist in virtue of the deep-down mathematical formulae on which the whole material universe is constructed.

Secondly, the New Astronomy differs from the old by a whole horizon in the notion of world-production.  About the middle of the century the theory began to be advanced that the worlds grew by accretion of matter; that they grew in the very paths which they now occupy; that they began to be with a small aggregation of matter rushing together in the line or orbit which the coming planet was to pursue.  The planetary matter was already revolving in this orbit and in the surrounding spaces.  It was already floating along in a nebulous superheated form capable of condensation by the loss of heat, but in particular capable of growth and development by the fall of surrounding matter upon the forming globe.  We must remember that in the primordial state the elements of a planet, as for instance our earth, were mixed together and held in a state of tenuity ranging all the way from solid to highly vaporized forms, and that these elements subsequently and by slow adjustment got themselves into something approximating their present state.

The New Astronomy contemplates a period when each of the planets was a germinal nucleus of matter around which other matter was precipitated, thus producing a kind of world-growth or accretion.  Thus, for instance, our earth may be considered at a time when its entire mass would not, according to our measurement, have weighed a hundred pounds!  It consisted of a nucleus around which extended, through a great space, a mass of attenuated planetary matter.  The nucleus once formed the matter adjacent would precipitate itself by gravitation upon the surface of the incipient world.  The precipitation would proceed as heat was given off into space.  It was virtually a process of condensation; but the result appeared like growth.

To the senses a planet would seem to be forming itself by accretion; and so, indeed, in one sense it was; for the mass constantly increased.  As the nucleus sped on in the prescribed pathway, it drew to itself the surrounding matter, leaving behind it an open channel.  The orbit was thus cleared of the matter, which was at first merely nebular, and afterward both nebular and fragmentary.  The growth at the first was