Soap Bubbles
and the Forces which Mould Them

111 THE FORCES WHICH MOULD THEM. 87 haves as I have described. The next photo- graph (Fig. 40), taken by the light of an instantaneous electric spark, and magnified three and a quarter times, shows a fine column of water falling from a jet. You will now see that it is at first a cylinder, that as it goes down necks and bulges begin to form, and at last beads separate, and you can see the little drops as well. The beads also vibrate, be- coming alternately long and wide, and there can be no doubt that the sparkling por- tion of a jet, though it ap- pears continuous, is really made up of beads which pass so rapidly before the eye that it is impossible to follow them. (I should explain that for a reason which will ap- pear later, I made a loud note by whistling into a key at the time that this photograph was taken.)