(3) In the meantime, or following afterwards, each one of the rings which were abandoned by the nebula, acquired, through the friction of its molecules with each other, an equal movement of revolution throughout its entire mass, so that the real velocities of the molecules furthest removed from the centre of the nebula were greater than those of the molecules nearest to its centre, and the ring revolved as if it were in one solid piece. Arrived at this stage the rings broke up and formed themselves into smaller nebulæ, each of which condensed into a globe or planet, and continued to revolve around the central mass in the same time as its mass had done when in the form of a ring. And some of these sub-nebulæ, imitating the example of their common parent more perfectly than others, abandoned in space in their turn smaller rings which in the same manner condensed, broke up, and formed themselves into smaller globes or satellites; all, as far as we know, except the rings of Saturn, which have not as yet been converted into satellites. TABLE I. ELEMENTS AND OTHER DATA OF THE SOLAR SYSTEM EMPLOYED IN THIS ANALYSIS. PART I.--SUN AND PLANETS. --------+-------------+----------+-----------------------+-----------+ |Mean Distance|Equatorial|Volume in Cubic Miles. | Density. | Name. | from Sun |Diameter | |(Water = 1)| | in Miles. |in Miles. | | | --------+-------------+----------+-----------------------+-----------+ Sun | -- | 867,000 |341,237,637,800,000,000| 1·413 | Mercury | 35,987,000| 2,957 | 13,537,968,847| 6·850 | Venus | 67,245,000| 7,660 | 235,334,728,260| 4·810 | Earth | 92,965,000| 7,918 | 259,923,832,335| 5·660 | Mars | 141,650,000| 4,185 | 38,378,333,333| 4·188 | Supposed| | | | | planet| 260,300,000| -- | -- | -- | Jupiter | 483,678,000| 87,680 | 352,940,162,601,626| 1·358 | Saturn | 886,779,000| 73,713 | 209,716,183,575,000| 0·736 | Uranus |1,783,383,000| 33,563 | 19,796,209,090,910| 1·302 | Neptune |2,794,000,000| 36,620 | 25,713,106,508,876| 1·132 | --------+-------------+----------+-----------------------+-----------+ | Volume at Density of | Time of Revolution | Name. | Water in Cubic Miles. | round Sun in Days. | | | | --------+------------------------+-----------------------+ Sun | 482,169,000,000,000,000| -- | Mercury | 92,735,000,000| 87·9692 | Venus | 1,131,960,000,000| 224·7007 |