218 



Mr. A. M. Worthington. 



bottom of which tlie drop descends, passing below the surface and 

 becoming completely submerged to emerge again at the head of a 

 column of adherent liquid, but with its upper portion apparently 

 unwetted by the liquid with which it has been covered. The column 

 then subsides, and the liquid of the original drop is seen to pass into 

 the well-known vortex ring which descends through the liquid. 



The influence of velocity of impact in modifying the phenomenon 

 is shown by the drawings. 



"When the drop is large, and the fall considerable, the rim thrown 

 up takes the form of a hollow crater-like shell of liquid, the mouth of 

 which closes over the drop, imprisoning air which may remain as a 

 bubble on the surface. This is the bubble seen when large rain drops 

 fall into water. Observations of the bursting of this bubble confirm 

 incidentally the explanation lately given by J. Plateau of the manner 

 of bursting of a soap bubble. 



The splash of a milk drop in petroleum and in olive oil is also 

 described. The course of phenomena is very similar to that in water, 

 modified however by the greater or less mobility of the liquids in 

 question. 



The impact of solid spheres is then described. The nature of the 

 disturbance produced, with a given velocity of impact, is found to 

 depend entirely on the state of the surface of the sphere. 



A polished and perfectly dry sphere of ivory or marble 1 to 3 

 centims. in diameter, let fall from a height not exceeding 1 metre, is 

 apparently wetted at once, and is seen to be sheathed with liquid 

 before the whole is below the average level of the surface. The 

 disturbance of the surface is very slight. 



The same sphere if rough or wet with the liquid in question, behaves 

 quite differently, making a very deep impression, similar at first to 

 that produced by a liquid drop, which finally becomes an almost 

 cylindrical column of air within the liquid, part of which afterwards 

 rises as bubbles while a portion descends in the wake of the sphere. 



The influence of roughness in hindering the spread of liquid over 

 the surface of the impinging sphere is then pointed out. 



At the close of the paper an explanation is put forward of the radial 

 ribs, arms, and striae which are a notable feature of all splashes. 

 Measurements of the annular rim bordering a thin central film into 

 which a drop falling upon a plate passes,* show that the number of 

 the lobes and arms which are subsequently observed, agrees well with 

 the number of drops into which such an annulus would theoretically 

 tend to split if unhindered by friction with the plate on which it 

 rests, and it is then pointed out that the effect of the connecting film 

 would be exactly such as to counteract the influence of this friction. 



* " Proc. Eoy. Soc," vol. 25, p. 500, fig. 4. 



