Paul Kotlarewsky, of St. Petersburg, has invented an instrument for
measuring or ascertaining the velocity of water and air currents.
Upon the shaft or axis of the propeller wheel, or upon a shaft geared
therewith, there is a hermetically closed tube or receptacle, D, which
is placed at right angles with the shaft, and preferably so that its
longitudinal axis shall intersect the axis of said shaft. In this tube
or receptacle is placed a weight, such as a ball, which is free to
roll or slide back and forth in the tube. The effect of this
arrangement is, that as the shaft revolves, the weight will drop
alternately toward opposite ends of the tube, and its stroke, as it
brings up against either end, will be distinctly heard by the observer
as well as felt by him if, as is usually the case, the apparatus when
in use is held by him. By counting the strokes which occur during a
given period of time, the number of revolutions during that period can
readily be ascertained, and from that the velocity of the current to
be measured can be computed in the usual way.
When the apparatus is submerged in water, by a rope held by the
observer, it will at once adjust itself to the direction of the
current. The force of the current, acting against the wings or blades
of the propeller wheel, puts the latter in revolution, and the tube,
D, will be carried around, and the sliding weight, according to the
position of the tube, will drop toward and bring up against
alternately opposite ends of said tube, making two strokes for every
revolution of the shaft.
[Illustration]
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