everal times between the adjacent masses. Magnus showed that the stream
of spherules may be diverted into another path by the attraction of a
powerfully electrified rod, held a little below the place of resolution.

Very interesting modifications of these phenomena are observed when a
jet from an orifice in a thin plate (Tyndall has shown that a pinhole
gas burner may also be used with advantage) is directed obliquely
upwards. In this case drops which break away with different velocities
are carried under the action of gravity into different paths; and thus
under ordinary circumstances a jet is apparently resolved into a
"sheaf," or bundle of jets all lying in one vertical plane. Under the
action of a vibrator of suitable periodic time the resolution is
regularized, and then each drop, breaking away under like conditions, is
projected with the same velocity, and therefore follows the same path.
The apparent gathering together of the sheaf into a fine and
well-defined stream is an effect of singular beauty.

In certain cases where the tremor to which the jet is subjected is
compound, the single path is replaced by two, three or even more paths,
which the drops follow in a regular cycle. The explanation has been
given with remarkable insight by Plateau. If, for example, besides the
principal disturbance, which determines the size of the drops, there be
another of twice the period, it is clear that the alternate drops break
away under different conditions and therefore with different velocities.
Complete periodicity is only attained after the passage of a _pair_ of
drops; and thus the odd series of drops pursues one path, and the even
series another.

Electricity, as has long been known, has an extraordinary influence upon
the appearance of a fine jet of water ascending in a nearly
perpendicular direction. In its normal state the jet resolves itself
into drops, which even before passing the summit, and still more after
passing it, are scattered through a considerable width. When a feebly
electrified body (such as a stick of sealing-wax gently rubbed upon the
coat sleeve) is brought into its neighbourhood, the jet undergoes a
remarkable transformation and appears to become coherent; but under more
powerful electrical action the scattering becomes even greater than at
first. The second effect is readily attributed to the mutual repulsion
of the electrified drops, but the action of feeble electricity in
producing apparent c