| 0.07 | .. beyond law }| | | | | | | | Percentage of}| | | | distance }| .. | 4.50 | .. | 22.54 within law }| | | | --------------+-----------+-----------+-------------+----------------- Our register as specified above will be the following:-- -----------+--------+-------+---------------------+-----------------+ Planet. | Rev. of Planet,|Accel. of revolution,|Density of Planet| |(in solar days) |(Neptune taken as 1) | | -----------+----------------+---------------------+-----------------+ Neptune. | 60,180.8600 | 1.0000 | 1.132 | Uranus. | 30,688.3000 | 1.9577 | 1.302 | Saturn. | 10,759.2198 | 2.8523 | 0.736 | Jupiter. | 4,332.5848 | 2.4833 | 1.358 | Asteroids.| 1,714.1876 | 2.5606 | ... | Mars. | 686.9796 | 2.4629 | 4.188 | Earth. | 365.2563 | 1.8808 | 5.660 | Venus. | 224.7007 | 1.6255 | 4.810 | Mercury. | 87.9692 | 2.5543 | 6.850 | -----------+----------------+---------------------+-----------------+ A good deal has been written about planets or other bodies existing between Mercury and the sun, especially about Vulcan whose existence seemed to be so certain, that his distance from the sun and period of revolution were calculated to be about 13,000,000 miles and 20 days respectively. Now, with what we have seen about the rate of acceleration of planets as their orbits approach the sun, we may endeavour to form some notion of where any within the orbit of Mercury may be found. If we take the same rate of acceleration we have found between Venus and Mercury--that is 2·5543, which may be looked upon as almost the general rate for all the planets--we find that there might be a planet revolving round the sun in 34·4436 days; but here we must stop, because, though we could make no objection to the existence of a planet with the period of revolution just shown, were we to take another equal step towards the centre of the nebula, the same acceleration of rotation would give us a planet, or ring for a planet, revolving round the sun in 13·4454 days; not much more than one-half the average of his rotation round his axis at the present day, which would knock on the head most completely the theory that each planet was detached from the nebula at the time that it was rotating with the velocity of the planet's orbit, or we should have to conclude that the nebula had passed, by a long way, its power to abandon matter through centrifugal force. No one could suppose that a ring for a planet could