Soap Bubbles
and the Forces which Mould Them

THE FORCES WHICH MOULD THEM. II^ musical notes, so that you could distinguish one note from the others. I can in the same way make the jet play a tune by simply making the nozzle rest against a long stick, which is pressed upon a musical- box. The musical-box is carefully shut up in a double box of thick felt, and you can hardly hear anything; but the moment that the nozzle is made to rest against the stick and the water is directed upon the india-rubber sheet, the sound of the box is loudly heard, I hope, in every part of the room. It is usual to describe a fountain as playing, but it is now evident that a fountain can even play a tune. There is, however, one peculiarity which is perfectly evident. The jet breaks up at certain rates more easily than at others, or, in other words, it will respond to certain sounds in preference to others. You can hear that as the musical-box plays, certain notes are emphasized in a curious way, pro- ducing much the same effect that follows if you lay a penny upon the upper strings of a horizontal piano. Now, on returning to our soap-bubbles, you may remember that I stated that the cate- noid and the plane were the only figures of