slowly with the bars extended. Without interfering with the spin, I now nip the clothes-peg and the weights drop, when you see that the spin immediately becomes much more rapid. Shrinking towards the axis quickens up the spin just as well as telling Mr. Heath to turn the handle quicker;

Fig. 51. and so we get our satellites formed because the planets shrink as they cool. There is another and perhaps a better way of making this experiment, using human arms instead of wooden ones. We place the human being on a turn-table (made to turn very easily by ball-bearings) with arms extended and holding a pair of dumb-bells (Fig. 52), and then give her a gentle