1894.] on the Splash of a Drop and Allied Phenomena. 297 



drop (Fig. 3), which, however, soon again emerges as the hollow 

 flattens out, appearing first near, but still below the surface (Fig. 4), 

 in a flattened, lobed form, afterwards rising as a column somewhat 

 mixed with adherent water, in which traces of the lobes are at first 

 very visible. 



The rising column, which is nearly cylindrical, breaks up into 

 drops before or during its subsequent descent into the liquid. As it 

 disappears below the surface the outward and downward flow causes 

 a hollow to be again formed, up the sides of w r hich an annulus of 

 milk is carried, while the remainder descends to be torn again a 

 second time into a vortex ring, which, however, is liable to disturb- 

 ance from the falling in of the drops which once formed the upper 

 part of the rebounding column. 



It is not difficult to recognise some features of this splash without 

 any apparatus beyond a cup of tea and a spoonful of milk. Any 

 drinker of afternoon tea, after the tea is poured out and before the 

 milk is put in, may let the milk fall into it drop by drop from one or 

 two inches above it. The rebounding column will be seen to consist 

 almost entirely of milk, and to break up into drops in the manner 

 described, while the vortex ring, whose core is of milk, may be seen 

 to shoot down into the liquid. But this is better observed by dropping 

 ink into a tumbler of clear water. 



Let us now increase the height of fall to 17 inches. Series III. 

 exhibits the result. All the characteristics of the last splash are 

 more strongly marked. In Fig. 1 we have caught sight of the little 

 raised rim of the hollow before it has beaded, but in Fig. 2 special 

 channels of easiest flow have been already determined. The number 

 of ribs and rays in this basket-shaped hollow seemed to vary a good 

 deal with different drops, as also did the number of arms and lobes 

 seen in later figures, in a somewhat puzzling manner, and I have 

 made no attempt to select drawings which are in agreement in this 

 respect. It will be understood that these rays contain little or none 

 of the liquid of the drop, which remains collected together in the 

 middle. Drops from these rays or from the larger arms and lobes of 

 subsequent figures are often thrown off high into the air. In Figs. 3 

 and 4 the drop is clean gone below the surface of the hollow, which 

 is now deeper and larger than before. The beautiful beaded annular 

 edge then subsides, and in Fig. 5 we see the drop again, and in Fig. 6 

 it begins to emerge. But although the drop has fallen from a greater 

 height than in the previous splash, the energy of the impact, instead 

 of being expended in raising the same amount of liquid to a greater 

 height, is now spent in lifting a much thicker adherent column to 

 about the same height as in the last splash. There was sometimes 

 noticed, as is seen in Fig. 9, a tendency in the water to flow up past 

 the milk, which, still comparatively unmixed with water, rides trium- 

 phant on the top of the emergent column. The greater relative 

 thickness of this column prevents it splitting into drops, and Figs. 10 

 and 11 show it descending below the surface to form the hollow of 



