upon the capillary tension, without
reference to initial disturbances at all.

Two laws were formulated by Savart with respect to the length of the
continuous portion of a jet, and have been to a certain extent explained
by Plateau. For a given fluid and a given orifice the length is
approximately proportional to the square root of the head. This follows
at once from theory, if it can be assumed that the disturbances remain
always of the same character, so that the _time_ of disintegration is
constant. When the head is given, Savart found the length to be
proportional to the diameter of the orifice. From (3) it appears that
the time in which a disturbance is multiplied in a given ratio varies,
not as d, but as d^(3/2). Again, when the fluid is changed, the time
varies as [rho]^1/2 T^(-1/2). But it may be doubted whether the length
of the continuous portion obeys any very simple laws, even when external
disturbances are avoided as far as possible.

When the circumstances of the experiment are such that the reservoir is
influenced by the shocks due to the impact of the jet, the
disintegration usually establishes itself with complete regularity, and
is attended by a musical note (Savart). The impact of the regular series
of drops which is at any moment striking the sink (or vessel receiving
the water), determines the rupture into similar drops of the portion of
the jet at the same moment passing the orifice. The pitch of the note,
though not absolutely definite, cannot differ much from that which
corresponds to the division of the jet into wave-lengths of maximum
instability; and, in fact, Savart found that the frequency was directly
as the square root of the head, inversely as the diameter of the
orifice, and independent of the nature of the fluid--laws which follow
immediately from Plateau's theory.

From the pitch of the note due to a jet of given diameter, and issuing
under a given head, the wave-length of the nascent divisions can be at
once deduced. Reasoning from some observations of Savart, Plateau finds
in this way 4.38 as the ratio of the length of a division to the
diameter of the jet. The diameter of the orifice was 3 millims., from
which that of the jet is deduced by the introduction of the coefficient
.8. Now that the length of a division has been estimated a priori, it is
perhaps preferable to reverse Plateau's calculation, and to exhibit the
frequency of vibration in terms of the other data of the proble