52 Causes of Water Spouts. 
This whirlpool, known in the country by the name of the gulf of 
Soltenstroem is a true spout of air in water, of which the foregoing 
experiment is a perfect representation on a small scale: and it may 
be considered as demonstrated that the gulf is produced by a whirl- 
pool formed at the bottom of a narrow and deep canal in which the 
tide waters are compressed, while the surface is motionless; for in 
fact whatever rapidity may be given to a whirl at the surface of wa- 
ter, the depression at the center will not increase in proportion to the 
velocity, because the ascending central current continually replaces 
the fluid expelled to the circumference; but, when the rotation is 
given to the water at the bottom, the replacement can take effect only 
at the upper part of the axis, and of course the descending current 
- must form a gulf at the surface. 
On the same principle may be explained the fact that certain turns 
in rivers, are dangerous to swimmers, for though no actual whirlpool 
may be found at the surface, it is possible that a whirl at the bottom may 
occasion a descending current not sufficient to produce a sensible de- 
pression at the surface, yet rapid enough to affect the swimmer, whose 
feet are near the center of activity. . 
If in the last experiment the surface of the water be covered with 
oil, the specific gravity of which being but little less, the descending 
current may be produced by a much slower rotation. When it is first 
fairly formed, the surface of the oil preserves its level. ‘The water: 
precipitated at the centre draws in the thin stratum of oil which it 
touches, and to which it adheres with a force not inconsiderable. 
hen the surface of the oil begins to circulate, a depression is 
produced, and a whirl of air is formed in the center which, however, 
never descends to the bottom, whence it mes be inferred that air has . 
less adherence to oil than to water. 
From the preceding facts, it is easy to perceive what must be the 
result when instead of being produced on the surface of the water, or 
at the bottom of the vessel, the whirl is found in the centre of the 
liquid column. ‘Two opposite currents are then formed, one ascend- 
ing and the other descending, which are carried along the axis to the 
centre of the primitive whirl. 
Fourth Experiment.—1 placed diagonally in the cael a Sal 
glass rod, with the inferior end drawn to a point, and fastened it into 
a groove fixed to the circumference at the bottom ; the other end was 
supported on the opposite edge of the vessel. 
