Provide a glass goblet about two-thirds filled with coloured water,
draw a fiddle-bow against its edge, and the surface of the water will
exhibit a pleasing figure, composed of fans, four, six, or eight in
number, dependent on the dimensions of the vessel, but chiefly on the
pitch of the note produced.
[Illustration]
Or, nearly fill a glass with water, draw the bow strongly against its
edge, the water will be elevated and depressed; and, when the vibration
has ceased, and the surface of the water has become tranquil, these
elevations will be exhibited in the form of a curved line, passing
round the interior surface of the glass, and above the surface of
the water. If the action of the bow be strong, the water will be
sprinkled on the inside of the glass, above the liquid surface, and
this sprinkling will show the curved line very perfectly, as in the
engraving. The water should be carefully poured, so that the glass
above the liquid be preserved dry; the portion of the glass between
the edge and the curved line, will then be seen partially sprinkled;
but between the level of the water and the curved line, it will have
become wholly wetted, thereby indicating the height to which the fluid
has been thrown.