On Impact with a Liquid Surface. 



217 



of up, the whole motion would be downwards. But even if the cracks 

 I mention did not take place, the contraction by cold would pull the 

 ice downhill, not up, whilst the expansion by increase of temperature 

 would tend to push the glacier downhill, so that these opposite actions 

 would produce similar effects in moving the glacier, or such part of it 

 as could be acted upon by external temperature, downwards. 



"I may also add that when a crack, however slight, is formed by 

 contraction, the cold is admitted into the body of the glacier, and 

 increases the contracting power or influences." 



On Impact with a Liquid Surface." By A. M. WORTHINGTON, 

 M.A. Communicated by Professor Osborne Reynolds, 

 F.R.S. Received January 27. Read February 16, 1882. 



[This paper is made up of the abstract already printed in the " Proceedings " — 

 here reprinted for the convenience of the reader — and a selection of the figures sent 

 in by the author, together with a description of them extracted from the original 

 paper.] 



The apparatus previously used* by the author for following the 

 progress of the splash of liquid drops impinging on a solid plate has 

 been improved. The main principle of the method by which succes- 

 sive stages are isolated and rendered visible remains the same, viz., 

 instantaneous illumination at any desired stage by means of the 

 primary spark of an induction coil ; but the timing of the illumination 

 is now effected by a timing-sphere let fall simultaneously with the 

 solid or liquid sphere whose impact is to be observed. The timing- 

 sphere strikes a plate whose height can be adjusted, and thereby 

 starts the mechanical action which results in the spark. 



The time interval between successive stages of the disturbance can 

 be measured to within a few thousandths of a second. 



The significant portion of the whole series of changes in most of the 

 splashes observed is comprised within about one- third of a second. 

 The impact of both solid and liquid spheres has been studied, and is 

 illustrated by several series of drawings which accompany the paper. 



Milk drops falling into water were found to produce a similar 

 disturbance to that resulting from the impact of similar water drops, 

 and were used for the sake of distinguishing the original liquid of the 

 drop from that into which it fell. With a drop about 5 millims. in 

 diameter, falling from less than 1 metre, an annular rim is raised at 

 the first moment of impact, bounding a hollow which is afterwards 

 characterised by regularly disposed radial ribs and arms, at the 



* " Proc. Eoy. Soc," vol. 25, pp. 261, 498. 



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