detached from the sun, nor the satellites detached from their 9. Not the least important addition to our knowledge several planets, but that these attendant bodies were all , of the sblar system is the proof that the system extends started in the distance and added on from without, we per-much beyond Neptune. In fact, the planets and comets are c e i e that the growth of inass and the collisions which have shown to be connected, by gradual transition, and thus it btaaght these bodies nearer a n d nearer the centres about . necessarily follows that the planetary system extends on alwhich they now revolve will necessarily have produced in-l most indefinitely. How many trans-Neptunian planets may dentations on the surfaces, as shown by the craters on the ~ be discovered by observation, it is difficult to predict; but moon. The origin of the lunar craters by the impact of j there should he two or three within the range of our presatellites is therefore directly demonstrated by an argument I sent means of exploration, at distances less than 100 astrohaving all the rigor required in the strictest mathematical I nomical units.
reasoning. Accordingly the lunar craters can be nothing !