but the irregularity of the last photograph almost masks the
resemblance.

SERIES XII.

_Engravings from Instantaneous Photographs (16/17 of the real size) of
the Splash of a Drop of Mercury, 4.83 mm. in diameter, falling 8.9 cm.
on to a hard polished surface._

[Illustration: 1]

[Illustration: 2

[Tau] = 0 sec.]

[Illustration: 3]

[Illustration: 4]

[Illustration: 5]

[Illustration: 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
glass 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 glass._

[Illustration: 1]

[Illustration: 2

[Tau] = 0 sec.]

[Illustration: 3

[Tau] = .0025 sec.]

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

[Illustr