into a single orb, it almost certainly represents the distraught state to which a once more compact congeries of them has been brought by planetary interference. For to just such fate must the stresses in it caused by Saturn have eventually led. Disruption inevitable to such a group the observation of comets demonstrates is daily taking place. When a comet passes round the Sun or near a planet, the partitive pulls of the body tend to dismember it, and the same is a fortiori true of matter circulating round a planet as relatively near as the meteoric particles that constitute Saturn's rings. Starting as a congeries, it was pulled out more and more into a ring until it became practically even throughout. And the very action that produced it tends to keep it as surprisingly regular as we note to-day.
No, the planets probably were otherwise generated and may have looked in their earlier stages as the knots in the spiral nebulæ do to-day. But this does not mean that we can detail the process.5
Taking now the congruities for guide, we proceed to see what they affirm or negative. Laplace, when he ventured on his exposition of the system of the world, did so "with the mistrust which everything which is not the direct outcome of observation or calculation must inspire." To all who know how even figures can lie this caution will seem well timed. The best we can do to keep our heads steady is to lay firm hold at each
