220 



Mr. A. M. Wortlrmgton. 



r= '1095. 



r= -167. 



Series I shows the splash produced by a milk-drop *496 centim. ins 

 diameter falling into water from a height of 8 centims., which differed 

 in no material respect from that due to a fall of 6 centims., which was 

 the lowest that I could observe. 



[In most of the figures of these and the succeeding series the dis- 

 turbing drop or sphere is in the centre; the white parts round it 

 represent those raised portions of the liquid which catch the light. 

 The numbers at the side of each figure give the time interval in 

 seconds from the occurrence of the first figure.] 



In respect of the agitation communicated to the liquid the pheno- 

 menon already differs from that which occurs with a fall of less than 

 1 centim. A hollow is formed with a raised lobed edge, into which the 

 drop descends, at first flattened out against the bottom (fig. 2). The 

 hollow as the drop descends becomes wider and deeper, but finally 

 (fig. 3) closes over the drop, which, however, soon again emerges as 

 the hollow flattens out, appearing first near, but still below, the surface 

 (in fig. 4) in a flattened lobed form, and afterwards rising as a column, 

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

 at first very visible. The origin of these lobes is explained at the 

 close of the paper. 



The column which is elevated being nearly cylindrical is approxi- 

 mately subject to the same laws of stability as a cylinder, and accord- 

 ingly divides into drops before or during its descent again 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 which an 

 annulus of milk is carried, while the remainder descends, to be torn 

 again a second time into a vortex ring, which however, is always liable 

 to disturbance from the falling in of drops which once formed the 

 upper part of the rebounding column. Thus it generally happens 

 that, owing to these subordinate drops, no distinct vortex ring is 

 formed. Sometimes, on the other hand, two are formed in quick 

 succession. It is, however, in the next series that the formation of the 

 vortex ring is most clearly traced, and it is on the evidence there- 

 afforded that the interpretation just given is really based. 



