A Study of Splashes

ling vertically into a liquid from a small height, and I should like to persuade the reader, if

"stone" marbles-and let one of these be well rubbed and polished with a dry handkerchief, and then dropped from a height of about 30 cm., or, sa

handling with hot or greasy fingers, it will be observed that the splash is singularly insignifi

still, if another marble be taken, which has been previously roughened with sand-paper, the resulting splash is totally different

ASH OF A RO

ies V shows that the liquid, instead of flowing over and wetting the surface of the sphere, is driven violently away, so that as far as can be seen from above the upper portion is, at first at any rate, unwetted by the liquid. The crater that is subsequently formed is very similar to that which was thrown by the liquid drop in Series I, the main difference being that in the present-case the crater is thinner in the wall and more regular. This greater regularity is chiefly to be attributed t

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re. "Baske

1·5 centim. Height

03

06

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here-(co

24

32

42

60

raceful column to a height which may be even greater than that from which the sphere fell. This is the emergent jet which one sees with the naked eye whenever a sufficiently rough sphere is dropped from a small height into water, but if we are to ascertain how this column originates, we mus

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here-(co

8 se

76

8 se

00

art that has already entered, while still higher in the figure may be discerned the summit of the sphere itself. The slight lateral displacement of the part below the surface is due to refraction consequent on the camera having been set with its optic axis not quite perpendicula

duces an angle where the two meet. This angle marks very clearly the level of the surface. Above the surface-line in Figs. 2 to 5 is seen the beaded lip of the crater which we have already viewed from above, but this is somewhat out of focu

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ugh sphere as seen

ntim. Height of

=

0 se

18

3 se

32

law of instability which regulated the sub-division of the jets and columns of earlier series. This law is the same whether the cylinder be of air surr

ssel, and is only detached and rises to the surface when the sphere strikes the bottom. Many years ago, through the kindness of the curator

how the two parts g

VI-(con

uced to a

5 se

0 se

54

e so accentuated that the upper part of this descending bubble is detached, and then the curious phenomenon may be

all sides. It is from the confluence of this inflowing liquid into channels which necessarily narrow as the centre is approached that the great velo

VI-(con

62

2 se

70

The first figure of this series shows very well how completely the liquid is driven away from the surface of the sphere the first moment of contact. The subsequent crater and bubble are of exquisite delicacy. This bubble, though it closes completely as in

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falling 60

03

7 se

17

33

m a splash into petroleum with 24·5 cm. fall.) But the last two figures, 4 and 5 (taken with a 32 cm. fall), show how a bubble which might otherwise have been permanent, is

gh sphere, I desire to call the re

f Series VI, p. 83, that a large volume of liquid has been displaced, much larger than the quantity required to form the crater wall. The inference is that the level of the surface has been slightly raised

ASH OF A SM

s series the sphere was of polished stone 3·2 cm. in diameter and fell 14 cm. The scale of magnification is 3/4. The second figure shows that the liquid, instead of being driven away from the surface as was the case with a rough sphere, now rises up in a thin, closely-fitting sheath which (see Fig. 3) completely envelops the sphere even before its summit h

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lashes viewed be

ing of th

55

lash into

cm.

0 se

64

lash into

m. f

0 se

82

haracterize the whole sheath in Fig. 3 and the left-hand (smooth splash)

tion is from behind as in Series X, in which the sphere was of highly polished serpentine st

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splash of a s

02

13

24

39

ifted without its flatness being sensibly disturbed. This conclusion was confirmed by a direct experiment. The not very wide vessel of Fig. A was taken and filled brimful with milk, and the lower edge of a card millimetre scale was placed just in contact with the liquid surface at one side. The reader should notice that the liquid is not qui

g.

g.

city of a compressional wave (i.e. with the velocity of sound) through the liquid, and is therefore almost instantly felt and

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ne sphere falling

3 se

06

8 se

11

3 se

14

om 12 to 32 millimetres-i.e. from about 1/2 inch to about 1-1/3 inches. No doubt with a very large sphere, taking a long time to enter, the splash would be controlled m