on to a hard polished surface._

[Ill.u.s.tration: 1]

[Ill.u.s.tration: 2

[Tau] = 0 sec.]

[Ill.u.s.tration: 3]

[Ill.u.s.tration: 4]

[Ill.u.s.tration: 5]

[Ill.u.s.tration: 6

[Tau] = 0195 sec.]

Series XII. gives an objective view of a mercury splash as taken by the camera. Only the first of this series shows any detail in the interior.

The polished surface of the mercury is, in fact, very troublesome to illuminate, and this splash proved the most difficult of all to photograph.

Series XIII. shows the splash of a drop of milk falling on to a smoked gla.s.s plate, on which it runs about without adhesion just as mercury would. Here there is more of detail. In Fig. 4 the central film is so thin in the middle that the black plate beneath it is seen through the liquid. In Fig. 8 this film has been torn.

Series XIV. exhibits the splash of a water drop falling into milk. The first four photographs show the oscillations of the drop about a mean spherical figure as it approaches the surface.

In the subsequent figures it will be noticed that the arms which are thrown up at first, afterwards segment into drops which fly off and subside (see Fig. 8), to be followed by a second series which again subside (Fig. 11), to be again succeeded by a third set. In fact, so long as there is any downward momentum the drop and the air behind it are penetrating the liquid, and so long must there be an upward flow of displaced liquid. Much of this flow is seen to be directed into the arms along the channels determined by the segmentation of the annular rim.

This reproduction of the lobes and arms time after time on a varying scale goes far to explain the puzzling variations in their number which I mentioned in connection with the drawings. I had not, indeed, suspected this, which is one of the few new points that the photographs have so far revealed.[5]

SERIES XIII.

_Engravings of Instantaneous Photographs (16/17 of the real size) of the Splash of a Drop of Milk falling 20 cm. on to smoked gla.s.s._

[Ill.u.s.tration: 1]

[Ill.u.s.tration: 2

[Tau] = 0 sec.]

[Ill.u.s.tration: 3

[Tau] = 0025 sec.]

(It was not found possible to reproduce satisfactorily the missing figures of this series.)

[Ill.u.s.tration: 7

[Tau] = 0128 sec.]

[Ill.u.s.tration: 8

[Tau] = 0149 sec.]

[Ill.u.s.tration: 9

[Tau] = 0149 sec.]

SERIES XIV.

_Engravings of Instantaneous Photographs of the Splash of a Drop of Water falling 40 cm. into Milk._

Scale about 6/10 of actual size.

[Ill.u.s.tration: 1]

[Ill.u.s.tration: 2]

[Ill.u.s.tration: 3]

[Ill.u.s.tration: 4

[Tau] = 0 sec.]

[Ill.u.s.tration: 5]

[Ill.u.s.tration: 6

[Tau] = 0056 sec.]

[Ill.u.s.tration: 7

[Tau] = 0163 sec.]

[Ill.u.s.tration: 8]

[Ill.u.s.tration: 9

[Tau] = 0182 sec.]

[Ill.u.s.tration: 10

[Tau] = 0197 sec.]

[Ill.u.s.tration: 11

[Tau] = 0262 sec.]

[Ill.u.s.tration: 12