72 Mr. S. Taylor on Colours shown by thin liquid [Jan. 31, 



box and placed near the resonator. With a tenacions film and nniform 

 bowing, this resulted in the formation of a fixed figure, consisting of 

 coloured bands, straight or curved, symmetrically arranged, and 

 generally accompanied by one or more colour-vortices rotating in 

 opposite directions. A single sweep of the bow usually sufficed to 

 call out such a figure from a previous state of colour- chaos, and, when it 

 was once established, careful bowing would keep it fairly steady for 

 some little time. While, however, its form remained thus constant, its 

 colours underwent a progressive series of changes as the thickness of 

 the film gradually diminished. Presently there would come a complete 

 break-up of the figure, often accompanied by a violent rotation of the 

 whole film, after which a different figure, generally of a simpler form, 

 would establish itself, to be in its turn, provided the film only held 

 out long euough, replaced by another and still more simple figure. 

 Sometimes, but much less frequently, the changes of form occurred 

 without a separating interval of disorder, the incoming figure sup- 

 planting its predecessor with kaleidoscopic abruptness, The most 

 interesting feature of these figures was their stationary colour- vortices, 

 arranged jDairwise, and churning round and round with a velocity 

 which seemed limited only by the loudness of the sound at command, 

 and by the capacity of the film for bearing the strain put upon it. The 

 fixed bands, viewed at any one instant, mostly presented a surprising 

 degree of complexity, with entire symmetry in the arrangement both of 

 form and of vividly contrasting colour. The general effect may, 

 perhaps, be compared to that of an elaborate " set-piece " of fireworks, 

 in which turbines of coloured flame play a conspicuous part. But the 

 great charm of the experiment lay in watching the successive changes 

 of form and hue which, beautiful from the very outset, became, as the 

 film neared its moment of dissolution, surpassingly gorgeous. It would, 

 I think, be difficult to point to a more splendid series of phenomena in 

 the whole range of physical optics. 



To give anything like a complete representation of the colour- 

 appearances observed would severely tax the utmost resources of pic- 

 torial art. The illustrations* appended to this paper are meant only 

 to convey a general notion of the phenomena which presented them- 

 selves. The memoranda for them were carefully taken down during 

 actual observation of the experiments, so that, in their broader features, 

 the figures given may be safely depended on. Minute accuracy of 

 detail could not, in dealing with such wayward phenomena, be secured, 

 except by a greater expenditure of time than was feasible. I propose 

 to make a few remarks on some of the colour-figures produced by the 

 mode of experimenting described above. 



Grentle bowing, and a film not too thin, usually called out fig. 1, in 



# Drawn by Mr. Daniel Wood, Master of the Cambridge School of Art, who most 

 kindly placed bis skill and scanty leisure at my disposal. 



