The Flow of Thin Liquid Films

IN the very interesting letter by Mr. W. G. Royal-Dawson in NATURE of March 23 on the above subject, the peculiar character of the stream-lines round a moving air bubble compared with those round a fixed solid obstacle may seem to some to require an explanation. As the writer of the letter offers none, may I be permitted to state what appears to be the cause of the conflicting currents shown in Fig. 4 of Mr. Royal-Dawson's letter?