624 



THE POPULAR SCIENCE MONTHLY. 



films to those made with soap-suds and glyceric fluid. We have 

 reversed the order in considering them, but it amounts to the 

 same thing in the end. 



Plateau's researches have been carried on by Brewster and 

 others, and the subject much enriched by later experimenters. 

 One of the most beautiful forms has not, it is believed, been pub- 

 lished. A sphere is outlined with three equal circles, making, 

 when joined together at equal angles, a globe with six meridians. 

 When this is dipped in the suds, a rather complicated figure ap- 

 pears. It is sometimes necessary to dip this frame several times 

 to get a perfect figure. From an axial edge of film three films 

 start out. Just half-way between the axis and the outside curve 

 of the sphere each of these three films meet two crescent-shaped 

 films from two of the wire meridians, curved so that the three 

 meet at the required angle. Sometimes when a bubble has been 

 caught in the system, and always if a small bubble is carefully 

 blown between two of the wires, a new figure will be formed. 

 In an instant, as though the change were wrought by magic, the 

 new figure flashes into existence. A long, six-sided, melon-shaped 

 figure reaches from pole to pole inside the sphere ; from each 

 edge of this figure, entirely unsupported as it is by the wire, a 

 crescent-shaped film reaches to each wire meridian. 



The figures formed 

 with the wire frames 

 are usually perfectly 

 symmetrical ; but some- 

 times, from the peculiar 

 form of the frame, sym- 

 metry is not consistent 

 with a union at the an- 

 gle of 120. The law in 

 such a case is obeyed, 

 and symmetry cast to 

 the winds. In Fig. 6, at 

 the first dip the figure 

 is very unsymmetrical, 

 though always the same. When a bubble is blown on the bottom, 

 the figure starts out perfectly symmetrical in form. 



Brewster has added many experiments to those of Plateau's. 

 The next one given is his, and a very curious one it is too. Two 

 rectangles are made of the copper wire ; one is slipped within the 

 other and held at right angles to it ; they are in this position 

 dipped into the suds. The system which starts into being can be 

 seen in Fig. 7. The central oval stands diagonally just half-way 

 between two of the angles made by the crossed frames. Now, if 

 the frames are gradually turned upon each other, which it is very 



Fig. 6. 



Fig. 7. 



