lts were obtained with other liquids, such as petroleum and alcohol.

It is easy to show in a very striking manner the paramount influence of
the condition of the solid surface. I have here a number of similar
marbles; this set has been well polished by rubbing with wash leather. I
drop them one by one through a space of about 1 foot into this deep,
wide, cylindrical glass vessel, lighted up by a lamp placed behind it.
You see each marble enters noiselessly and with hardly a visible trace
of splash. Now I pick them out and drop them in again (or to save
trouble, I drop in the place of these other wet ones), everything is
changed. You see how the air is carried to the very bottom of the
vessel, and you hear the "phloisbos" of the bubbles as they
rise to the surface and burst. These dry but rough marbles behave in
much the same way.

Such are the main features of the Natural History of Splashes, as I made
it out between thirteen and eighteen years ago. Before passing on to the
photographs that I have since obtained, I desire to add a few words of
comment. I have not till now alluded to any imperfections in the timing
apparatus. But no apparatus of the kind can be absolutely perfect, and,
as a matter of fact, when everything is adjusted so as to display a
particular stage, it will happen that in a succession of observations
there is a certain variation in what is seen. Thus the configuration
viewed may be said to oscillate slightly about the mean for which the
apparatus is adjusted. Now this is due both to small imperfections in
the timing apparatus and to the fact that the splashes themselves do
actually vary within certain limits. The reasons are not very far to
seek. In the first place the rate of demagnetization of the
electro-magnets varies slightly, being partly dependent on the varying
resistance of the contacts of crossed wires, partly on the temperature
of the magnet, which is affected by the length of time for which the
current has been running. But a much more important reason is the
variation of the slight adhesion of the drop to the smoked watch-glass
that has supported it, and consequently of the oscillations to which, as
we shall see, the drop is subjected as it descends. Thus the drop will
sometimes strike the surface in a flattened form, at others in an
elongated form, and there will be a difference, not only in the time of
impact, but in the nature of the ensuing splash; consequently some
judgment is req