THE AMERICAN APICULTURIST. 



61 



and sides by a rubber strip and 

 kept in place by four clamps. In 

 this tank is placed a portion of a 

 soap solution, which is raised in 

 bubbles by a current of air blown 

 into it through a fine glass tube. 

 As the bubbles are formed, their 

 tendency to become spheres in vir- 

 tue of the force of cohesion in their 



the soap films at such a large in- 

 cident angle that they are almost 

 entir^y reflected, and so are tinged 

 with the rich colors resulting from 

 the interference of rays that fall 

 on thin films. 



We thus have before us a proof 

 of the tenuity of a layer which is 



between the limits of 



and 



liquid walls is overcome by the 

 capillary attraction of the sides 

 of the tank. By consequence 

 the films extend across the tank 

 perpendicular to the walls, and the 

 pressure of one bubble upon another 

 causes the formation of polygonal 

 forms, analogous to those that 

 we see in cross sections of wood 

 fibre. The accompanying figure 

 gives an idea of the appearance that 

 the tank presents when thus filled 

 with bubbles, but does not and can- 

 not portray the beauty of the pro- 

 jection of it which may be made 

 upon a screen. The pencil of rays 

 passing from the condensing lens of 

 a stereopticon is convergent ; and as 

 a consequence many rays fall upon 



TTeVff^of an inch, the latter limit 

 being reached when the color of 

 the film disappears. 



The same illusti'ation also aflTords 

 us an exemplification of the prin- 

 ciple, shown in nature in the 

 structure of the honeycomb,that the 

 pressure on each other of equal 

 circles produces an hexagonal struc- 

 ture. Where, in consequence of 

 the regularity of the current of air, 

 we have produced bubbles nearly 

 uniform in size, we notice that the 

 polygons formed are six-sided, and 

 that those of a difl^erent number of 

 sides exist where there is a diversi- 

 ty in the size of the air masses. 



Friends' Cetitral School, Phila- 

 delpliia. 



