*Civil and Hydraulic Engineering Department, Indian Institute of Science, Bangalore.
**Department of Civil Engineering, University College of Engineering, Burla, Sambalpur, Orisa.
Techniques of measuring velocities in open channels and conduits are quite old, but the devices developed for measuring tangential velocities are of comparatively recent origin. Mention is made in this paper of some of the different techniques adopted by various investigators. The most suited method namely, the “Optical Method” is described in detail as this method was made use of in carrying out some basic studies on “Vortex Motion”.
